
Have you loosened the brake lines from the knuckle? Those hard lines can be picky about cross threading, and if you havn't loosened them from the knuckle, then there isn't much give to line the threads up right.

That flat "clip" holds the brake line to the bolted-on bracket. Use pliers or vice grips to slide it off the line (you'll have to wiggle it a bit) and you should have enough slack on the line.