Check that the Editor Profile Parameters allow the required tags
You can skip this step if you do not wish to allow script, style or php tags but still need to allow onmouseover / onmouseout tags.
In the JCE Control Panel, click on the Editor Profiles button.
Click on the Profile name that the user, usergroup or component is assigned to, eg: 'Default'
Click on the Editor Parameters tab, then on the Options tab.
Configure Joomla! Article filters
By default Joomla! 'cleans' content on saving, removing script tags, event attributes (such as onclick, onmouseover etc.) and style tags.
A simple article parameter change is all that is required to fix this.
Joomla! 2.5 & Joomla 3
- In the Joomla! Global Configuration, click on the Text Filters tab.
- For the Super Users group, or any other trusted user group, set Filter Type to No Filtering. Make sure that you only set this option for user groups that can be trusted as setting the Filter Type to No Filtering will essentially allow the user to include any html in an article.