The styles are disabled because in sharepoint 2010 the styles and the markup styles menus are exclusive to wiki pages.
To fix this problem you will have to change your field in the schema.xml like this
Hope that it helps if not please post a comment
To fix this problem you will have to change your field in the schema.xml like this
<Field
ID="{BF6BD5D0-F44A-4B62-99D7-A92A1465DFBF}"
Name="RichtextMenuEnabled"
DisplayName="
RichtextMenuEnabled "
Type="HTML"
RichText="TRUE"
RichTextMode="ThemeHtml" />
and you will have the same field without having to delete/Create the list with the menu enabled
Hope that it helps if not please post a comment

