It would be helpfull if you post your DECLARE for GetPrinterDriver.

>The error returned from GetLastError() is
>1780 = "A null reference pointer was passed to the stub."
>
>i have tried setting the second parameter to 'chr(0)' as specified in help ("...Pointer to a null-terminated string that specifies the environment (for example, "Windows NT x86", ...")
>
>but the result is the same. the function returns 0, and the bufferlength needed is not returned.
>
>
>
>>You've to check error generated by GetPrinterDriver to make sure that it's 'buffer too small error' not something else.

>>* Get the size of the buffer required
>>IF GetPrinterDriver(PrHandel, "", 1, "", 0, @RecvdBufferLen) = 0
>>	IF GetLastError() <> 122   && The buffer too small error
>>                *   Do something
>>		RETURN .F.
>>	ENDIF
>>ENDIF
>>

See Enumerating printer forms under Windows NT/2K/XP FAQ #22445 for how to handle API errors.
>>
>>>Why would the following not return the size need for the returned data (windows xp, Vfp 6 Sp5)? the printer is a network printer, but also installed on this machine. I am trying to get the name of the PrinterDrive installed for this printer.

>>>PrHandel = 0
>>>?OpenPrinter("\\print01\Plan1", @PrHandel, 0)
>>>?PrHandel
>>>
>>>RecvdBufferLen	= 0
>>>
>>>?GetPrinterDriver(PrHandel, "", 1, "", 0, @RecvdBufferLen)
>>>
>>>Test		= space(RecvdBufferLen)
>>>*EnvString		= "Windows XP"
>>>EnvString		= ""
>>>
>>>?GetPrinterDriver(PrHandel, EnvString, 1, @Test, RecvdBufferLen, @RecvdBufferLen)