Car wont go into D4
 

Hello,
I recently got a 97 Integra (auto). Its visually showing its age but mechanically its pretty sound (from what I can tell). The problem is that when I move the gear selector it slides right by D4 and settles into D3. It goes in every other selection perfectly and without problem, but its like D4 isn't selectable. Also, the car runs, drives, reverses, and parks no problem, its just the D4. Any suggestions?