Help, can't knot David

Hello, so i am having a bit of trouble. I am trying to knot my medium-firm David analy but by the time i hit the knot i feel a small sharp pain which I'm guessing is a second sphincter wall? How do i get through this part and finally knot it.

 

Take your time is step 1. It may take a couple of weeks to work up to it. Put it in and hold it at the point where it starts to be uncomfortable and hold it there for a few minutes. This will cause stretching to take place. Each day you should be able to get a little further until you finally get it all the way in. Use a lube injector and that will help make sure it's well lubed on the part going in and the part already on the inside since the anus tends to squeegee the lube off.