theme not compatible with WYSIWYG? - 6.x

this is a strange issue - I have installed both TinyMCE and Yahoo YUI Editor, and played with all manner of input formats trying to get them to work - then, when switching to Bluemarine, I find that the problem is really non-existent, or theme specific.

To be more detailed, there seems to be some issue where the paragraph tags, line breaks, bold text and so forth aren't working with this theme when input with the WYSIWIG - again, the issue disappears when switching to a core theme.

This is 6.x version.