[Braillenote] entering german

[will]

Hi

I have set my german computer braille table as the default for typing 
german.
However when i type dots
1, 2, 5, 6, 8
for U umlaut the unit just bleeps at min, as though i ahve done an invalid 
keystroke what i am doing wrong please?
I set the unit up for eight dot computer braille?
regards, will