Floating point division

Good evening! I am new to CUDA.

I am trying to divide two floating type numbers simply by / (division) in kernel. But the result always returns the MAX_NUM of floating data type.
In debugging mode, I set breakpoint on the line contains /(division), but program does not stop at breakpoint. No debugging msg feedback too.
My cuda computing ability is only 1.1. Does anyone meet similar problem? Any input is welcome,

Thanks!

share a part of your code here, please