I have a "community forum" blog with three categories (Forums). When a user tries to "Start a Topic" the form includes a drop down box "Forum" with the three categories present. However, the user is unable to select any of them. No matter which category is clicked, the box closes back to "Select Forum...".
Here's the relevant snippet of html from the page:
Select Forum...
Reported on Movable Type 4.2

It appears my blurb of html was eaten. Here's a second try
` Select Forum...
<optgroup label="Abc"> </optgroup> <optgroup label="Def"> </optgroup> <optgroup label="Ghij"> </optgroup> </select>`I think this maybe to the result of you not having sub-categories. As the documentation explains, forums require two levels of categories: one define the "Forum Groups" and the second level defines each individual "Forum."
This is not very well documented.
The top level categories translate to top level groups of forums. The subcategories are the forums themselves.
This feels like a hack though.
Thank you Byrne and Matt. Your spot on. As soon as I demoted the categories by nesting them within another category, the drop down box worked.
Sorry for the noise.