If you are using assembly, then Craig's and peter's answers will solve your problem.
If you use Accumulator, then always try to PUSH accumulator and PSW both to the stack, as 99% cases using accumulator, will modify PSW as well.

You can use 8052 simulator available on the left side panel of this site.
Craig is so generous, he is not promoting his own product at this site.

If you could not find any simulator so mail me, I will send you one.

Simulator solves most of the problems usually a begineer has to dealt with.

Goodluck,

Rauf