AT&T User - MMS not working

[Alaskan]

I bought an unlocked Xperia Pro for use on AT&T's network.  I have the data working but can't get the MMS to work.  I have been in touch with both Sony & AT&T and both just point the finger back to the other. 

I have tried the following Access Point settings unsuccessfully. Are there any AT&T users out there who can assist me? Please?

Name: AT&T

APN: wap.cingular

Proxy: leave blank

Port: leave blank

Username:WAP@CINGULARGPRS.COM

Password:CINGULAR1 (yes this is in CAPS)

Server: leave blank

MMSC: http://mmsc.cingular.com

MMS Proxy: wireless.cingular.com (also tried 66.209.11.32)

MMS Port: 80 (also tried 8080)

MCC:310

MNC:410 (note: this could also be 310, 41 or 15)

APN Type: leave blank (also tried internet+mms) (also tried mms)

[Alaskan]

Yes, I wondered about whether that might help.  I haven't checked to see if my number is up yet. I have only used Android about a month and am finally getting the feel for it.  I figured if I jump to ICS, I'll have a new learning curve.

[Uliwooly]

I don't know when it'll be released for the "a" variant, but you can manually update it

Don't forget to mark the Correct Answers & Helpful Answers

[Alaskan]

Hooray! That worked!  I deleted all my APNs including this one, then re-entered just this one and BOOM, my MMS is now working (and data is still fine).  I am so grateful to you, uliwooly.  Thank you very very much!