did you have the hammer cocked back when you depressed the safety lever? Is the safety lever located on the slide like the Walthers? It is not always recommended to just let the hammer drop as a result of using the safety lever, if that is the way this pistol functions - sometimes they go 'bang'.
Same thing with older P-38s - they recommend you ease the hammer down with your thumb when you depress the safety lever.
Hope I got this one right.................. Mikey.