Sim reader replacement, will not read a sim!

Hello ifixit,

I come with a question about sim reader replacements on iPhones. I just started trying to replace these, so far I've done 3 phones and none of them will recognize a sim card. They were physically damaged readers that I replaced, no water damage of any sort. When I take a multimeter to the finished product, everything ohms out the same as a perfectly working sim reader that's never been replaced. I'm getting all 4 anchors attached, as well as the 6 pins in the middle and the 2 at the back for the little spring arm. I've been using 400 degrees fahrenheit to remove the readers as well as covering unwanted areas in kapton tape. When I put the new reader on, I notice it doesn't sit down perfectly flush, but everything is connected and seems to have correct resistances. For the life of me I can't get them to read a sim though, or pick up anything! Please help!