It is very rare that I can get a mms to go through using handcent. Whenever I send a mms I just use the stock message app. Its a pain, but its the only way to get it to work. Also, if you are trying to send to an iphone, you have to type a caption with the pic. It will not send if you don't add a caption. Just get in the habit of always typing a caption. Hope this helps.