Vacation foiled again

I'd hoped to take this next weekend off and get a much needed break from the theater for a while.  As soon as he heard this, the DM decided he wasn't going to stand for it and swung by for a surprise inspection.  So I spent yesterday enduring a constant littany of "you-suck-you-suck-you-suck."  The quiet satisfaction I felt at the fact that he had to search so hard for things about which to gripe was squelched by the constant undermining of my authority.
Then he cornered and quizzed my assistant managers so that he could ascertain how well they could function in the projection booth if I wasn't immediately on hand for a couple of days.  Although they could thread the film through the projectors just fine, and knew how to troubleshoot problems like tangling and replacing bulbs, he found them lacking in other areas.  Apparently, they didn't know what some of the parts were called, and couldn't completely take the projector apart and clean it.  These skills were essential to running the theatre for the weekend.  I'm not sure how, but he assured me they were as he vetoed my vacation request.
It wasn't until afterward that he shot me a challenging look with eyebrows raised and it all fell into place.  This wasn't just another case of him being an ass; he was actually making some kind of vindictive attack.  He didn't give a crap about how much the assisstant managers knew about projection.  Even if they'd measured up to whatever rediculously high standard he set, he would have found some other reason to shoot down my vacation request.
Now this would normally be the time when someone would say, "So he wants to play hardball, does he?  Fine, bring it on!"  But the truth is that I suck at hardball.  I need to find some other way to resolve this.