I have an unlocked HTC Trophy and i'm connecting to ATT's network with a SIM.. everything works excpet the MMS Texting i can send out video/photo texts but unable to recieve

I get a text message from "UNKNOWN"
and then says message not found in the body of the message..

i tried the connection settings app and that didn't work acually before i put that on the phone i got the images but only as a link and it wouldn't download..

I tried some developer app fix.. didn't work..

Some manaul APN settings , rebooting umpteen times.. contacted ATT and they have registered my IEMI but still nothing.. HELP!!!!!