Read the whole thread, and you will see that the CORRECT syntax is

?Set("printer",1)
?Set("printer",2)
?Set("printer",3)

Set("printer",0) is illegal, and was corrected and updated, but the update was overlooked in some of the other messages.

>>maybe the problem is sp2 :)
>>~M
>>>
>>>Using 8 sp2. The following line:
>>>
>>>

>>>?Set("printer",0)
>>>

>>>
>>>returns the "Function argument value, type, or count is invalid." error.
>
>Mark,
>
>It returns the same error message in VFP9. But
>

>?SET("Printer")
>

>with no second parameter returns the printer's status.
>
>Regards,