[RESOLVED] problem with .net version

[xperator]

hi guys.
sorry but i have to explain all these for you maybe you can tell me what am i doing wrong

here is the story:
i made a program a month ago and i gave it to the customers.
recently they report some bugs and i fixed them. when i send the new version installer to them, they have some problems running it.

and here is the history :
i used vs 2008 to write it, but i removed vs 2008 and installed vs 2010 last week. when i opened my project to start fixing program bugs it asked for convert wizard so i did it.
i made changes and build it. i use installshield and i add framework 3.5 Sp1 as a prerequisites.
note : i was using inno setup first time. so i changed the installer too.

so i tried installing the program on my machine.
i just noticed that i have only .net framework 4 installed my own system. so i have no idea how the program runs without any problems on my own system. i have even tried installing it on another machine who had framework 3.5. it it work on that too.

the error shown on customers machines is related to framework version. everytime i send them a new version they have some problem installing/running it.
i am really confused i don't know which step i did wrong.

these are the things that i want to ask:
1.does the convert wizard which i did, changes my application framework version from 3.5 to 4 ?
2.is there a difference between framework 3.5 and 3.5 sp1 ?
3.does .net framework 4 include 3.5 ? if not, how is that possible the application worked on my system ?