Image button not working

Hi all,

first I would like to state I try to post my question/report in the correct place, if it is not: sorry, I am a drupal newbie as well as a TinyMCE newbie.

I'm not fully sure what the issue is so I'll try to explain as clear as possible.

I installed TinyMCE to be able to add images when adding contents. Everything works out great, I see the menu, I can use it, can add buttons, delete buttons, ... Only when hitting the image button I get a popup with my default theme stating "Page not found". The page it is going for is: http://www.jefspalace.be/cms/modules/tinymce/tinymce/jscripts/tiny_mce/t...

I have tried installing IMCE but the problem remains, deleting the two TinyMCE tables and reinstalling makes no difference. I'm using drupal 5.1 together with TinyMCE 2.1.0

Hoping to get some help, kind regards,

Jef