Cannot activate 3gs on 4.0

[still in school]

- Phone was on ios4 and I wanted to restore to sell it.
- Shsh were saved for 4.0 on Saurik's server.
- I restored to original 4.0 by directing to Saurik's server
- Put old ATT sim to Activate but phone shows "No Service"

Any idea what's going on?

 

[still in school]

Mod's can lock the thread. I've figured it out.