[jQuery] jQuery and Mootools Problem

Hi,
i use jquery and mootools.
But i have a problem, after loading the site, i became an js error
this.$events[type].keys has no properties
mootools.v1.11.js
Line 2878
Here is a screenshot: http://gfx.kj187.de/jqueryMootoolsProblem.tiff
Has anybody an idea ??
regards kj187 (julian)