Hi moritz, so if I remember right Max's new CustomUI 2.0 for MoI v4 uses this element that is in the default MoI v4 CommandBar.htm as the target for where to place the added buttons:

            <span id="CommandBarCustomUI">
            </span>

This element appears to be missing in this alternative UI. If you add it in that may solve it.

But also I would think you would see an error message pop up when the CustomUI startup script tried to do something to this element but it wasn't there, however you didn't mention any error message being displayed?

- Michael