Xs400 charging problems!

Soooo This is driving me insane.

New battery and stator new regulator!

But still, still! Bike will charge with lights off but will not charge with lights on!

Led rear light but high beam on the front a rather big bulb? Battery was showing a decent voltage on on tick over and goes up when reverd to what it should, bur when you put lights on nothing!

Faulty regulator?

Please help me!