BLI F7 number board lights

[dadret]

I have a BLI F7 with DCC & Sound and I can't seem to get the number board lights to work.  I have replaced the LED circuit board twice with new ones from BLI.  I know that the F11 on my MRC Prodigy Advance turns them on and off but it does not seem to do anything.  I suspect that there is an electrical problem within the loco but before I return the entire engine to BLI I was wondering if anyone has any ideas - maybe I'm doing something wrong.  (When I replaced the circuit board this time the number board lights came on briefly so I tried turning them on/off with the F11 button but now they are off and will not come on.  The headlight, mars light, and cab lights work OK and respond to the appropriate F command.)