Username and Password do not match Error
First verify your username and password is valid, by logging into http://pictures.sprintpcs.com and logging in using your login information. Next you should change your password, this will prevent the Picture Mail Website from requesting a password change in the future. Now you should be able to send using the sMMS. If after successfully completing these steps, you still have problems, contact me.
BTW This is from the FAQ located in the sticky. Also you may want to post there, you'll get quicker responses.