I hate dotted lines. It often seems to me that there are more dotted ones than solid ones...

If you have requirements of another team, you should be raising a change/service request with that team's manager and allowing him/her to manage it entirely, or if there is a lot of work involved, the other manager can transfer staff to you as 'managed resources' for x days or weeks. These 'resources' then report directly to you for that period of time and get assigned back to their regular manager afterwards.

Otherwise you're constantly arguing over whose work is the most urgent and the developers end up trying to run multiple projects concurrently, get pushed from pillar to post and everything gets delivered late.