Yeah Tamiya has two sets of Paints, TS and PS.

TS is for hard plastics such as ABS bodies etc. PS is for Polycarbonate.

Look on your can and see which it may be. If TS, then it will not adhere correctly. If its PS, it could be from the prep.

With Tamiya PS Paints, I usually clean the body really good with dish soap and water, at least twice. then I basically blow the water left from rinsing out, and then let it airdry prior to painting. This has never failed when using the spray can paints, for myself.