Delchem ballvalve fitting

I'm a novice to plumbing but thought I could fit this. I did so but think I omitted to do something with the split pin so the water did not stop flowing through the inpipe. What do i need to do with the pin? Would appreciate a little help here.

Have realised my error - I did not adjust the screw. Have now done that and water flow has stopped, except that it is dripping very very slowly. The float seems to be fine. What could it be?

What exactly have you fitted?

The entire 'chem valve assembly, including inlet pipe? Just the valve part? Just the washer?

The entire assembly, including inlet pipe, but using the old float - seems fine. It may be successful. I was just concerned about a very slow drip that does not seem to have been completely shut off. But the water level has stayed well below the outlet pipe all afternoon so perhaps I am worrying about nothing. I'll see how it goes.

Thanks for your support. I'll re-post if it proves a problem.

It can take a few hours for the washer and seat to become accustomed to each other.