as with any paint - prep is the key to longevity. with plastic even more so. rather than just taping it off & painting it you should have taken it off completely, sanded it down to make rough not smooth, gotten a good adhesion promoting primer and sprayed the entire thing. when you tape it off it leaves edges of the paint that will begin to lift and peel. krylon may advertise their paint as a "one shot no primer needed" product, but you have to keep in mind all the trim pieces are thin plastic that flex. the flexing will cause stress cracks in the paint and it will start peeling away.