Try Settings > Software Updates > Update Profile AND Update PRL.
If that doesn't work try this. You will need your MSL that's the service code referenced in step 4. Sprint should give it to you if you tell them you need to reset your phone and do a hands free activation.
Phone Reset Steps
Note: This process only clears out the previous phone number and ownership information; it does not clear everything off of the phone (contacts, photos, applications, etc.).
- Turn your phone On by pressing the Power button
- On the phone dial pad, enter ##72786#
- Select Reset
- When prompted for Service Code, enter the 6-digit code you received in the Activate your new phone process in My Sprint
- Select Done
- When you see the message, SCRTN is change to factory default value for DSS, select Done
- Your phone will turn off and turn back on and then go through the activation process
- When you see the message Your device is now active, press OK