It is working correctly. This is its expected behavior. Also note that there is a "Cancelled" Boolean output that will be TRUE when the user cancels the file dialog.
You need to use the "Not a Number/Path/Refnum?" function to make this comparison. Please see the attached VI. A path with the text "" is not the same thing as . You can tell if it is , because you will not be able to insert a cursor into the path control/indicator/constant.
