Requiring jQuery in a userscript breaks tag autocomplete

I'm working on a small script and I noticed one odd thing: if I add a line
// @require http://ajax.googleapis.com/ajax/libs/jquery/2.1.0/jquery.js
to a script that doesn't do anything and runs on Danbooru, the autocomplete list that appears when you start typing a tag just doesn't appear. Why is this happening?

I don't really write userscripts, but for starters, check error console in your browser? Also see if other javascript- or jquery-related things (like floating edit box) work fine. Also, danbooru already uses jquery 1.1 and customized autocomplete from jquery-ui, see https://github.com/r888888888/danbooru/tree/master/vendor/assets/javascripts for details - maybe that's just a version conflict.