>:( That means shell32.dll version installed on your computer does not have this function implemented.
>
>Check what version you have (should be at least 5.0; I have the 6th on WinXP). This is code to check Shell32 version:
>

>#DEFINE DLLVER_PLATFORM_WINDOWS  1
>#DEFINE DLLVER_PLATFORM_NT       2
>
>DECLARE INTEGER DllGetVersion IN shell32 STRING @pdvi
>
>LOCAL lcBuffer
>lcBuffer = Chr(20) + Repli(Chr(0), 19)
>
>IF DllGetVersion (@lcBuffer) = 0
>	? "*** Shell32.dll"
>	? "Major version:", buf2dword(SUBSTR(lcBuffer, 5,4))
>	? "Minor version:", buf2dword(SUBSTR(lcBuffer, 9,4))
>	? "Build number: ", buf2dword(SUBSTR(lcBuffer, 13,4))
>	? "Platform:     ", Iif(buf2dword(SUBSTR(lcBuffer, 17,4))=1,;
>		"Windows", "WinNT")
>ENDIF
>
>FUNCTION buf2dword(lcBuffer)
>RETURN Asc(SUBSTR(lcBuffer, 1,1)) + ;
>	BitLShift(Asc(SUBSTR(lcBuffer, 2,1)),  8) +;
>	BitLShift(Asc(SUBSTR(lcBuffer, 3,1)), 16) +;
>	BitLShift(Asc(SUBSTR(lcBuffer, 4,1)), 24)
>

>
>This is MSDN link for IsUserAnAdmin function
>http://msdn.microsoft.com/library/default.asp?url=/library/en-us/shellcc/platform/shell/reference/functions/isuseranadmin.asp

Why does it say WinNT on Win XP?