FRUSTRATION

I had a project in mind using pintucks, so i sent away for a pintuck foot for my serger. It's just 2 little pieces of clear plastic, $28.95!
I proceeded to unthread the setup for 4-thread overlock, and change to coverstitch mode. Even though I've done it before, I had to slowly take it step by step becauses, as Jon likes to point out, "I have the memory of a dead elephant." Once I had it all set up with coverstitch throat plate and all the settings, plus the new pintuck foot, I proceeded to try it out on scraps.
The results were not pretty. Either the left needle thread broke, or no pintuck was made, or both. By no pintuck, i mean the stitch just looks like a regular coverstitch, with no ridge between the needles for the tuck.
Must be something wrong with my threading that is causing the left thread to break. I may have solved that problem. But still no tucks are being made. After trying most of the afternoon, I had to give up. I'll start fresh tomorrow.