ODE XP - Error installing application

Greetings all

I've developed an application with MS Access 2002 and distributed it with
a 
Setup program generated with Packaging Wizard. The setup works fine with 
Windows 98 and 2000. But when I try to install the software in a computer 
with Windows XP installed, it ends with a message:

     Visual Basic 6.0 Setup Toolkit
     -------------------------------
     The Office System Pack cannot be installed on this system because it 
requires Windows NT 4.0 Service Pack 6 or later


I don't understand this message, because the operational system is Windows

XP, a version well later than NT 4.0. Does anyone knows something to
correct 
this instalation package?


Thanks

Sidnei Cordeiro