Cargo door won't lock

2004 Chevy Tahoe.

Cargo door will not lock with the remote nor using the switch inside
the door. All the rest of the locks on the left and right doors front
and back work fine.

Checked fuses (can you get more cryptic for the abbreviations?) under
the hood and under the instument panel. All look fine.

Any idea what it could be? Everything else in the back power wise
seems fine.

Adam