Strange..??

Just in setup-part of my prog I have make 8 bit-reg of one byte:

;********************

Tempo DATA 32h ;Temporary byte

;********************

AA BIT 32.0h ;Temporary checkbits
BB BIT 32.1h
CC BIT 32.2h
DD BIT 32.3h
EE BIT 32.4h
FF BIT 32.5h
GG BIT 32.6h
HH BIT 32.7h

;********************

Now I want, in one particular routine reset all values such as:

MOV Tempo,#0

but it seems that it doesent work, so obviously, I have to reset
each bit.

CLR AA
CLR BB .......

Can anybody explain why ????

On the other hand, it works properly to define a ram-byte as
singel bit-reg for temporary use.