Changing Default Printer Setting under Windows NT 4.0

I'm looking for a little assistance with Windows NT,

I have coded an function to change the default printer by using the Enum
printer, Printer_Info_5 structure and changing the Attributes value.  This
works find in Windows95 but in Windows NT the process completes without
errors but does not change the default printer setting.

Any advise would be helpfull !!