Not able to receive picture messages

This has happened not only on two different phones but on two completely separate accounts (both T-Mobile, if it matters), and I've had every OS from 4.0 to the most current OS6 that's been released by the carrier. My sister currently has the exact same phone on the exact same shared account, both with BB data plans, and has no trouble getting picture messages, while I get nothing, not even the text-only part. I had no idea until people at work started complaining that I wasn't answering some of their texts. I know of three other people with the same phone and carrier who have no trouble receiving pictures and no one remembers changing any settings. In my message options, under MMS, both multimedia reception and automatic retrieval are set to "always." what gives?

Have a read here, particularly the part about half way down related to resending service books, pretty sure that should cure it Support: Set up T-Mobile services on unsupported BlackBerry� devices

Sometimes they don't all download properly at first boot, sounds as though your MMS one is missing