HK 45c decock problem

Hey guys, so I traded one of my pistols for a 45c. Has a 5/6 detent in it and ambi safety. Gentleman had it set up like a 1911 in where the safety does not work as a decocker. Anywho, swapped out detent to 1/2 and safety to only left side......still will not decock.....what am I missing?? Thanks in advance, tried looking it up but my Google/Forum foo is weak by any standards! Been on here for a bit, sad that this is my first post!