system.web -- pls help

Question

Hi, im new at c#.net and i have some problem about my project. I wrote a program which sends email with using systme.web. My project is working at my computer; but my program is not working at different computer. I think i have a mistake about system.web.dll when i building my setup project. What should i do when i am building setup project. When i writing program, i used .net sdk v1.1. Now my version is 2.0 i can be make any problem. Please help meee thanks.