For this reason some of our and other extensions may not work correctly.
If you use System - Mootools Upgrade plugin you may encounter problems with extensions under the IE9 browser e.g.
DJ-Catalog2 or DJ-Flyer components and its modules.
To solve the problem you should update MooTools version provided by the mentioned plugin.
Please read the following instruction to learn more how to fix the problem and update mootools version: