If I Replace the BYTE with STRING in VFP, if get the famous Fatal exception error C00005 !, When i use INTEGER, it works but returns wrong values.

Yes the variable names have to be the same as the one in the DLL, it was just a typo.

A Variable Type BYTE in VB is i Think an Integer value from 0 to 255, so why is INTEGER dont work in VFP.

Tanks