Hey... I have the same problem.... and the bad news:
There is nothing you can do..
I tried to contact an Admin to get this fixed:
- postet in the Forum
- Wrote to the Support
- pvssyd in EA Livechat
There was no reaction at all.
Next unlock is at level 40 I guess so u have to wait until you are 40 and when u are 50 there will be still a Locked Weapon.