spoiler and lights dont like each other!

[Riley 0]

sorry if this is a major repost,but is this a common problem?

 

spoiler works fine on the switch with lights off.

switch also works with lights on as in up/down but starts jerking up and down when i let go of the switch and cant make its mind up :?

 

if i have the lights on it dosnt come up at all or starts going up and down again real fast.

 

i checked the earths at the back as well as the n0. plate lights and all seems fine.

 

thanks,neil.