Problems with a plunger type trip lever assembly

I am having a problem with a plunger type trip lever assembly. It doesn't close the drain to stop the water from coming out. The tub and assembly are new and I have adjusted it from end to end. I even attached a string to the plunger and moved it a little at a time up and down that way, it still lets the water out. What could be the problem?

If it was a very inexpensive trip and waste, the barrel might not be sealing off the tee. I always install the foot-lok stop or lift n turn drains. Less problems and hair clogs are localized.