Great advice from Randmguy. I like the reach shape too.
Anyway, if you hear 4 pins clicking you may have 4 pins picked or you may not. Overset pins will click when you let off the tension too.
So if any of the four pins themselves are overset, it may prevent the remaining pin from setting. As mentioned, it may very well be that pesky first pin!
If the first pin feels springy, then something else may be preventing it from setting. If it feels solid and the key pin is stuck in the up position, then it has probably been overset. Some locks feel different (BEST, for instance), but with kwikset you may notice a floppy keypin when you set a pin stack.
If you think something may be overset, try lightening the tension till you hear a click and then check things out by tapping at the pins some more.
I assume you have good tension, very important. Have you tried placing your tension tool at the top of the keyway!? This may help to stop you from tapping that first pin so much on the way in and it will give you more room if you want to try an extra tall hook.
So at least you'll be hitting the pins a little different...
It is important to try different things because sometimes a certain pick or method will place a pin stack in a position that prevents another stack from setting easily. Which may make things more difficult or even very frustrating.
If I didn't just make things more confusing, then maybe I helped.
Once you've opened that lock up a few times you will probably look back and wonder why you couldn't get it before.
Each lock you encounter will have it's own quirks. This is where it's like solving a puzzle. Once you find the method that your lock is particularly vulnerable to, you'll be opening it very quickly and consistently each time.
Just remember every lock is different!
Have fun!
I have never seen so many in one post!