I don't know why but on phones through sprint you can not do this! Sprints 8330 Curve along with a few other phones do not suport MMS or SMS / picmail! There is a work around I have only used a few times but it takes a few extra steps to complete but worked each time.
Instead of texting the person with pic / mms, you email the person using their mobile number along with the correct carries email. With attached photo or clip.
Here is a list of extensions
@mms.att.com
@tmomail.net
@vzwpix.com
@pm.sprint.com
@mms.mycingular.com
@message.alltel.com
@mms.uscc.net
@messaging.nextel.com
@vobl.com
@myboostmobile.com
Posted from my CrackBerry at wapforums.crackberry.com
If that's true, then it's one more thing to ***** at Sprint about...
Seriously that's a joke. Dan Hessy wonders why they're going into the tank. A Curve is basically a multimedia phone and I'm finding out it might not support MMS? That's not right. Tsk Tsk