problem ont hpwm on the pic16f767!!

i have been using a 16f876a of late for my dmx project. with many thanks to to you all for the help i have recieved.. i have changed chips to the pic16f767 chip as this has 3 hpwm units on it.. works great no code change same pins outs etc... except lol n heres the crunch... i cant seem to get the 3rd hpwm channel to work? ie,

HPWM 1,dval0,5000
HPWM 2,dval1,5000
HPWM 3,dval2,5000


works fine for 1 and 2

works fine for 1 and 3

if i try to use all 3 i get the following.

ch1 works fine all of the time.

ch 2 flickers very faintly.

when i engage ch 3 ch 2 works fine????

but no ch 3 !!!!!

i can only assume this is down to some register setting that i have overlooked.

does anyone know the proper setup of registers to enable 3 hpwm's on the 16f767??? please.....

this is the 1 and only problem i have left on my dmx decoder..... apart from pcb design bla bla lol.......