Doesn't recognize my number as a vaild mobile number

I'm a new customer I just started my contract service on 12/12/2012....Today I tried to register an account on My T-mobile.com, put my number in and I got an error message that says my number is not a valid mobile number This is an entirely new number not a ported one from my pervious phone service. I will appreciate ANY help I can get on here from other users and hopefully TECH SUPPORT that works for T-mobile