I'm not a plumber, so I don't know whether this is the recommended solution, but I had a similar problem attaching an elbow to the ballcock in a toilet cistern. I simply use more PTFE sealing tape so that the fitting starts to tighten up a couple of threads before the male part reaches the "end of the line" on the threads in the female elbow. If you discover that you've gone too far, and the fitting can't be tightened further around to the correctly aligned position, don't loosen it, to re-align as it may leak. Undo and re-apply tape again. It might be helpful to post on plumbing forums to get a second opinion.