Why doesn't this work?

[nemok]

HICON hIcon;
LPBYTE lpBuffer;

hIcon=dlg.GetIconHandle();

lpBuffer=(LPBYTE)::GlobalLock(hIcon);

HANDLE hUpd=BeginUpdateResource("D:\\n.exe",0);
UpdateResource((HMODULE)hUpd,
 RT_ICON,MAKEINTRESOURCE(1),
 MAKELANGID(LANG_NEUTRAL,
 SUBLANG_DEFAULT),
 (LPBYTE)lpBuffer,
 GlobalSize(hIcon));
EndUpdateResource(hUpd, FALSE);

GlobalUnlock(lpBuffer);

I'm using this code to take the icon from an exe and replace the icon in another exe, but it doesn't work. Every time lpBuffer is empty after GlobalLock. the hIcon handle is retrieved by ExtractIcon();
What am I doing wrong?
Please help!