tuwood

I used to do a lot of soldering in the Navy & the secret is to get it clean, use flux, isolate the heat, & heat both pieces equally. Then the solder just flows right in.

I take the two parts & clean & flux them, just as you did. Then I use a cinder block as a work surface (because it doesn't absorb the heat) & place the iron on top of the larger piece. I pretty much wait a minute or so for it to completely heat it up. I then slide the iron down to whre it's touching both the surfaces to be joined & hold it there for a minute or so. Then I take my solder & touch it between the iron & the metal piece. If it's at the right temperature the solder should start melting onto the metal & not beading up. If it cools & doesn't stay melted on your metal then it's not hot enough yet.
Once the solder starts to flow all around your material your soldering then you can twist it around or use your soldering iron to shape the joint. You should have a nice smooth joint that almost seamlessly connects the two points. The thing your trying to avoid is a cold solder joint which isn't really bonded to one side or the other.

Hope this helps.