well that stuff is no good on plastic
what ya need is a paint that is made to stick to plastic like ppg`s dbc system has a product just made for plastic and only interior parts
all that rattle can is garbage paint and i believe it`s laquer or enamel
not goin to stick
if ya want pieces painted send them to me i will take care of it for ya
and i can do it in any color too
but ya you need to use interior paint
but my guess is why it chipped off is due to poor preping,
1: clean the parts with warm soapy water
2: then scuff with a grey scuff pad
3:then clean again using dx 330 it`s a wax and grease remover
4: put the base coat on dry to meduim not wet
5: let the coats of color dry 5 to 10 minutes depending on weather if it`s real humid out wait longer
hope that helps
any questions will be more than happy to help