2 handle shower defective?

I had a leaky shower head so I replaced both handles (valves, stem, and seats) but there still seems to be a problem. When I turn the cold side, water comes out and then shuts off. I have to continue to turn the handle another half turn in order for water to come out again. I have no idea if it is leaking inside the wall

Could it be that I bought the wrong brand. I had no idea what brand I had and had someone from the local Home Depot match it up for me.

Could it be that I have a faulty replacement kit or did I somehow break something (washer...) when I installed it. At first it was very difficult to even turn the handle so I replaced a plastic washer with some plumber's thread/string ...

Any ideas?

I would pull it all apart and start over before you assume you did anything wrong. Make sure you have the handle loose (stem). Then you tighten the bonnet (the part that holds the stem) Did you also change the seats? If not you should.

Getting stuff from the box sores is always a bad idea.

I hope you saved the original stems... You might need them if smockman didnt do a good job of matching them up. Look for a loose washer by the sounds of it.

I did not save the originals. I did replace the seats.

Why would the hot side work fine but there is a problem with the cold side?

Should I get a plastic replacement washer instead of using the pipe string?

Is there such a thing as a universal kit I can use?