Door locking problem!

Hello guys, im new here and i jsut bought a e36 325ia 95, and im having problems with my lock pin. it just simply dont stay in lock position, and does not lock any doors when i press it (on the driver's side) I feel that its loose, i just feel that little spring holding it, i press it down its and when i release it goes up. can you guys help me?
Sorry for the bad english.
Sorry for the bad english.