Gear shift does not come out of P position, unless I press unlock button

What is your question?

Today I replace its brake light switch. After the change, the shift comes out of its P position only if press a screw driver into the opening near the shift to hold the shift unlock key down. I do not need to hold the unlock button when shifting from Neutral to Drive or Reverse, or vice versa, or Reverse to Parking, only from Park to Reverse. I check a few fuses, which were OK. Perhaps,I did not check the right one. Has anyone have insight into this problem? Thanks