Worcester DT20RF Problem?

Hi

Not a major showstopper but just wondered if anyone has expereinced the same problem?

I bought a DT20RF Receiver and Room Thermostate for a Worcester-Bosch Greenstart Junior 28i Condensing Boiler

Everything works as it should EXCEPT the backlight on the Receiver (the bit in the boiler!) doesnt work

The green led's that sit above the 'select' work, and the LCD display all works, but the manual does clearly state that there should be a 'backlight' for low light operation. I didnt notice it at first...so put the boiler/covers all back (and its in a really tight cupboard/corner!)

Im sure that the plug/pins were inserted correctly - and Im sure if they werent then the unit wouldnt work at all...in other words I really dont want to remove the casing etc to check

Does anyone think that a loose pin MIGHT be the problem, or just a faulty receiver backlight?

Anyone had similar problem??

Thanks

Also (forgot in original post) - on the back of the ROOMSTAT, there is a small 'jumper' that says 'min 16 operation' - I cant find any reference to that in the manual

What is that for, and why would I want it 'enabled' ??

Ta