Tailgate latch does not close

[gbsk]

I have a '96 Legacy. The tailgate latch will close BUT not all the time. I can sometimes open it but once I open it I have to manually push the latch down before I close it or it will not close properly. If I do not do the, I have to take e big screwdriver to pry the latch up. I did put some lithium grease on the latch on the outside of the latch and it works a little better but I still have to push the latch in the down position before I close it. How can I fix this? Thanks.