LED rear light issues

[Scoot655]

ive recently changed the rear light on my chopper to an LED unit.chop runs standard 12v ac set-up but cant get light to work right.its either on permanent with the brake light(pedal makes no difference0 or the rear light is on and it goes out when the pedal is pressed!?
have tried all sorts of wiring combinations and nothing works.lights worked fine when I had a standard type rear light fitted.

[Toddy]

Which type is it ? As the wiring are different on some , Have you got it earthed correctly ?

[Marty ULC]

Have you got a 12v battery you can use to test the unit off the scoot? I had similar issues with a cheapo Chinese one, used my motorbike's battery to test it and it turned out that the unit's brake light circuit wasn't lighting the leds up any brighter than the rear. Was dirt cheap so got another one and it works fine.

[Scoot655]

the earths are good and im sure that both the stop and rear lights work on it.will try it off the scoot with a dc supply and see what happens!?may just have to bite the bullit on this one.thanks for your help!