Perhaps you need immediate instead of direct addressing?

MOV A,80h will fetch the value from location 80h (some SFR to be precise) and place its current value into the accumulator.
If you want to write the number 80h instead, you need to prefix it with a #

MOV A,#80h will load the ACC with the value 80h
MOV A,80h will load the ACC with the value stored in location 80h

Just a shot into the dark - it might help though :)