99 Accord Clutch went

OK so we got the car out of reverse and into my garage. Tearing it apart will begin soon.

SO just to recap:

The car goes in and out of gear when its off but when running you cant get it in gear.
When the car is off theres half pressure in the peddle and you can see the slave pushing the fork make and forth.

So why would the car not be able to go into gear if the fork seems to be working properly from the outside. Just wondering before we start this job