here's one of my posts from another thread:

"well it's not sticking cause you're not soldering correctly. You should not heat the solder and then let it drip onto the joint. Instead tin the tab by heating the tab from the bottom and then applying solder on the top. The solder should melt almost instantly and form a nice even bulge over the tab. Then take the wire and put it on top of the tinned tab. Then heat from the bottom. The solder will melt and the wire will make connect with the tab. The displaced solder (from the wire being forced to touch the tab) will climb up the side of the wire end creating a very strong solder joint. It's hard at first but it gets easy fast. I've soldered about 20 connectors that way and it works every time. As for the chart, that's what RCCA says, not me."