Hi
Please can someone help me figure out what I am doing wrong?

I have had so many attempts at soldering 925 ready assembled cuff link backs to my fingerprint cufflinks made from PMC. I am using soldering paste and a gas torch, and think I have follower all the advice I can come across but still no joy. The soldering paste just bubbles and stays brown and then can be flaked away. I have tried heating slowly and quickly but neither way seems to help.

Anyone got any bright ideas? I am starting to think there is something wrong with my paste, but they do say its a bad workman that blames his tools! ha!

Thanks Hannah