1 1/4"

I have a 1-1/2" PVC (white) p-trap. Connecting at the tailpipe side is no problem. But connecting at the 1-1/2" (white) wall side pipe is a problem. The captive nut on the (Charlottesville 1-1/2") wall side pipe is thinner, larger (2" ?) and does not come down over the end of the pipe. I have...