Baquero
If you have every thing clean and using proper flux you should not have a problem. I am wondering if you are getting your metal hot enough to accept the solder. Its flowing the solder but not sticking to the metal because your not getting the metal hot enough. Looks like your doing this on an anvil or something maybe its taking to much heat away from the piece.

Just a thought, I am sure there is more advice out their. Those Texas guys do a lot of soldering on metal. Come on boys. help him out.
