Crossbow Error on Mists of Pandaria.

so i have a pandaren hunter rn and i'm doing a quest where i have to defeat 6 tenshui warriors atop balance poles. generally i'd shoot them with my ranged weapon (crossbow) except i can't because if i use the "attack" option the system says "interrupted" and if i choose any of my abilities e.g. arcane shot or steady shot, it says i need to have a ranged weapon equipped for that. my crossbow is equipped, though, and when i try equipping a new one (i have a higher-level one in my bag; it's level five and i'm level ten) the system says "you cannot do that right now". anyone else have this problem? is this a bug?

When this happened to me, my pet did all the fighting for a while... until I died and the bug ended.