Gear selector interlock

I have a '96 F150 4WD and when I put my foot on the brake to select drive, the shift lever will not move. It feels like the safety interlock is not disengaging, is there a common problem with this mechanism that anyone knows about ?

Thanks.

Check the brake light fuse or the brake light switch. The connector to the brake light switch are also known to break on Fords.

A thousand thanks way2old, it was the brake light fuse that had blown. Possibly caused by defective trailer wiring, I will have to check that out.
Your help saved me a lot of time.

Glad to help.