Back door handle installation?

I took off the two door handles on my daughter Toyota Matrix to paint the door while still on the car. I was able to replace the front door outside door handle so that it is working. The back door handle is giving me problems. I put it together and it doesn't work. I watched a few YouTube videos but didn't find any with this issue. The only thing I found was the a red plastics fork had to go over a metal part. Nothing I have tried has made it work.