unlocked blackberry storm 9530 wont send mms!! HELP?

[AN(DRE)S]

i have t mobile and on my plan i have unlimited text and picture messaging, now this is the problem i just got a unlocked blackberry storm 9530, ans i can text without a problem but when i try to send a mms or picture message however u wanna call it i get a lil pop up saying "No MMS Service Record, message cannot be sent. You will only be able to save draft" i googled it up to see what can i do to fix it all i found was to go on service book and register to get a new copy of my service book, but still nothing, can someone plz helo me out with details? by the way the guy who had the blackberry had a t mobile plan on it and was able to send mms.