Solder or Epoxy?
I think your problem may be the propane torch. If your putting the flame directly on the joint to be soldered, chances are your burning off all the flux before you ever put the solder to the joint. I think you would get much better results using an iron. Place the iron on the bottom side of the joint and the solder on the top of the joint, as the solder melts it will wick through and give you a nice strong joint. Also use the smallest diamiter solder you can get, (Radio Shack has some real thin stuff) it will melt much faster than the big think stuff so you'll get solder into your joint before all the flux is gone.