Shimano Tiagra Rear Derailleur - Barrel Adjuster Won't Screw In My rear derailleur barrel adjuster has unscrewed completely and now I can't get it back in.

Is it likely that I've damaged something here, or is there some special technique to screw in barrel adjusters that I don't know about!?
just in case someone else stumbles upon this while trying to solve a busted thread for the barrel adjuster, I managed to solve this yesterday by rethreading the aluminium derailleur housing gradually by going with smaller size thread screws first, then finishin with m5, that's the size of the barrel adjuster screw thread, which was in my case still intact. The problem was that a bike mech was lazy and didn't want to adjust the cable tension manually, so he/she unscrewed the barrel adjuster so far out of the derailleur, that it only held itself in place by 2/3 bends, in which case the leverage on those bends in case of an impact on the barrel adjuster is so great, that the soft aluminium thread inside the housing has no chance of withstanding that.