//////////////IM HEADER: //////////
/*	Struct	*/
struct regdata {
	char username[USERNAME_LENGTH];
	char pass[PASS_LENGTH];
	char fullname[FULLNAME_LENGTH];
	char emil[EMIL_LENGTH];
	char birthday[BIRTH_LENGTH];
	int level;		//kliens nem töltheti ki/kliens kitöltése figyelmen kívűl hagyandó
};
//////////////////////ListView/////////////////////////
HWND initListView(HINSTANCE hinst,HWND hwndParent){
	HWND hList;
	LVCOLUMN LvCol; // Make Coluom struct for ListView

	InitCommonControls();
	hList = CreateWindow(WC_LISTVIEW, "", WS_CHILD | WS_VISIBLE | LVS_ICON | /*LVS_EDITLABELS |*/ WS_BORDER | WS_TABSTOP
						, 0, 0, CW_USEDEFAULT, CW_USEDEFAULT,hwndParent, NULL, hinst, NULL);
	if(hList == NULL){
		Error("Hiba a user manager ablak(ListView control failed) készítésekor");
	}
	if(!InitListViewImageLists(hList,hinst)){//elsőnek kell initializálni!!!
		Error("Ikonlista betöltése sikertelen!"); 
	}

	SendMessage(hList,LVM_SETTEXTBKCOLOR, 0,(LPARAM)CLR_NONE);
    SendMessage(hList,LVM_SETEXTENDEDLISTVIEWSTYLE,0,LVS_EX_FULLROWSELECT); // Set style

	// Here we put the info on the Coulom headers
	// this is not data, only name of each header we like
    memset(&LvCol,0,sizeof(LvCol)); // Reset Coluom
	LvCol.mask=LVCF_TEXT|LVCF_WIDTH|LVCF_SUBITEM; // Type of mask
	LvCol.cx=0x28;                                // width between each coloum
	LvCol.pszText="Állapot";                     // First Header
 	LvCol.cx=0x42;
	// Inserting Couloms as much as we want
	SendMessage(hList,LVM_INSERTCOLUMN,0,(LPARAM)&LvCol); // Insert/Show the coloum
	LvCol.pszText="Felhasználónév";                          // Next coloum
    SendMessage(hList,LVM_INSERTCOLUMN,1,(LPARAM)&LvCol); // ...
	LvCol.pszText="Jelszó";                       //
    SendMessage(hList,LVM_INSERTCOLUMN,2,(LPARAM)&LvCol); //
	LvCol.pszText="Teljes név";                              //
    SendMessage(hList,LVM_INSERTCOLUMN,3,(LPARAM)&LvCol); //
	LvCol.pszText="E-mail";                            //
    SendMessage(hList,LVM_INSERTCOLUMN,4,(LPARAM)&LvCol); //
	LvCol.pszText="Születési dátum";                      //
    SendMessage(hList,LVM_INSERTCOLUMN,5,(LPARAM)&LvCol); // ...same as above

	return hList;
}

BOOL AppendListItem(HWND hList,struct regdata REG){
	BOOL bSuccess=0;
	LVITEM LvItem;
    memset(&LvItem,0,sizeof(LvItem)); // Reset Item Struct
	//  Setting properties Of Items:
	LvItem.mask=LVIF_TEXT | LVIF_IMAGE;   // Text Style
	LvItem.cchTextMax = 256; // Max size of text

	LvItem.iItem=ListView_GetItemCount(hList);          // choose item  
	LvItem.iSubItem=0;       // Put in first coluom
	LvItem.pszText="Icon helye";
	LvItem.iImage=REG.level;
    bSuccess =SendMessage(hList,LVM_INSERTITEM,0,(LPARAM)&LvItem); // Send to the Listview

	LvItem.iSubItem=1;
	LvItem.pszText=REG.username;
	bSuccess &=SendMessage(hList,LVM_SETITEM,0,(LPARAM)&LvItem); // Enter text to SubItems

	LvItem.iSubItem=2;
	LvItem.pszText=REG.pass;
	bSuccess &=SendMessage(hList,LVM_SETITEM,0,(LPARAM)&LvItem); // Enter text to SubItems

	LvItem.iSubItem=3;
	LvItem.pszText=REG.fullname;
	bSuccess &=SendMessage(hList,LVM_SETITEM,0,(LPARAM)&LvItem); // Enter text to SubItems

	LvItem.iSubItem=4;
	LvItem.pszText=REG.emil;
	bSuccess &=SendMessage(hList,LVM_SETITEM,0,(LPARAM)&LvItem); // Enter text to SubItems

	LvItem.iSubItem=5;
	LvItem.pszText=REG.birthday;
	bSuccess &=SendMessage(hList,LVM_SETITEM,0,(LPARAM)&LvItem); // Enter text to SubItems

	return bSuccess;
}

/////////////////
BOOL InitListViewImageLists(HWND hwndLV,HINSTANCE hinst) 
{ 
	BOOL bSuccess=FALSE;

	InitCommonControls();

	HICON hiconItem;     
    HIMAGELIST himlLarge; 

    himlLarge = ImageList_Create(32, 32, ILC_MASK, 5, 1); 

	for(int i=ICO_ADMIN;i<=ICO_OFFLINE;i++){
		hiconItem = LoadIcon(hinst, MAKEINTRESOURCE(i)); 
		if(ImageList_AddIcon(himlLarge, hiconItem)== -1)
			Error("Addicon nem sikerült!");			
		DestroyIcon(hiconItem);
	}
    if(ListView_SetImageList(hwndLV, himlLarge, LVSIL_NORMAL) != NULL){
		bSuccess = TRUE;
	}
	else
		Error("Hiba: %i",GetLastError());
	return bSuccess;
} 

////////////////////////////////////////////////////

Bitte aussagekräftigere Titel verwenden

MfG SideWinder

ListView_SetImageList liefert NULL auch im Erfolgsfall, wenn vorher keine
ImageList gesetzt war !

Returns the HIMAGELIST handle to the previous image list, if any, or NULL otherwise.

Setze mal ein
SetLastError(0);
vor ListView_SetImageList und teste dann nochmal.

Gruß
RB

/******************************************************************************

   CreateListView

******************************************************************************/

HWND CreateListView(HINSTANCE hInstance, HWND hwndParent)
{
DWORD       dwStyle;
HWND        hwndListView;
HIMAGELIST  himlSmall;
HIMAGELIST  himlLarge;
SHFILEINFO  sfi;
BOOL        bSuccess = TRUE;

HICON hiconItem,hiconItem2;

dwStyle =   WS_TABSTOP | 
            WS_CHILD | 
            WS_BORDER | 
            LVS_AUTOARRANGE |
            LVS_REPORT | 
            LVS_EDITLABELS |
            LVS_SHAREIMAGELISTS |
            WS_VISIBLE;

hwndListView = CreateWindowEx(   WS_EX_CLIENTEDGE,          // ex style
                                 WC_LISTVIEW,               // class name - defined in commctrl.h
                                 NULL,                      // window text
                                 dwStyle,                   // style
                                 0,                         // x position
                                 0,                         // y position
                                 0,                         // width
                                 0,                         // height
                                 hwndParent,                // parent
                                 (HMENU)IDC_LISTVIEW,       // ID
                                 g_hInst,                   // instance
                                 NULL);                     // no extra data

if(!hwndListView)
   return NULL;

ResizeListView(hwndListView, hwndParent);

//set the large and small icon image lists
himlSmall = /*(HIMAGELIST)SHGetFileInfo( TEXT("C:\\"), 
                                       0,
                                       &sfi, 
                                       sizeof(SHFILEINFO), 
                                       SHGFI_SYSICONINDEX | SHGFI_SMALLICON);*/
                                       ImageList_Create(16, 16, ILC_COLOR24 | ILC_MASK, 5, 1);

himlLarge = /*(HIMAGELIST)SHGetFileInfo( TEXT("C:\\"), 
                                       0,
                                       &sfi, 
                                       sizeof(SHFILEINFO), 
                                       SHGFI_SYSICONINDEX | SHGFI_LARGEICON);*/
                                       ImageList_Create(32, 32, ILC_COLOR24 | ILC_MASK, 5, 1);

for(int i=ICO_ADMIN;i<=ICO_OFFLINE;i++){
		hiconItem = LoadIcon(g_hInst, MAKEINTRESOURCE(i));
		hiconItem2 = LoadIcon(g_hInst, MAKEINTRESOURCE(i+5));
		if(ImageList_AddIcon(himlLarge, hiconItem)== -1 || ImageList_AddIcon(himlSmall, hiconItem2)== -1)
			MessageBox(0,"Addicon nem sikerült!","gg",0);			
		DestroyIcon(hiconItem);
	}

if (himlSmall && himlLarge)
   {
   if(SendMessage(hwndListView, LVM_SETIMAGELIST, (WPARAM)LVSIL_SMALL, (LPARAM)himlSmall)==NULL)
                                Error("Hiba SMALL: %i",GetLastError());
   if(SendMessage(hwndListView, LVM_SETIMAGELIST, (WPARAM)LVSIL_NORMAL, (LPARAM)himlLarge)==NULL)
                                Error("Hiba LARGE: %i",GetLastError());
   }
else
    {
    MessageBox(0,"q","q",0);
    }

return hwndListView;
}

WARUM?

ich denke mal daß die LV vorher keine ImageList besitzt also kann auch keine
vorhergesetzte ImageList-Handle zurückgegeben werden, daher ist == NULL falsch !

Beim ersten setzen der ImageList ist Rückgabe == NULL kein Fehler.

Oder kommt der Fehler auch, wenn Du die Funktion zweimal nacheinander aufrufts ?

Grüße
RB

Danke für die Hilfe Kumpel!