The WPANumbers standard action only seems to work (i.e., create numbered list items) if the WPABullets action has not previously been used. If WPANumbers is triggered after WPABullets, a bulleted list is inserted instead of a numbered list, and both the Numbers and Bullets toolbar buttons are shown as depressed.
I am using a WPRichText control attached to a Developer Express toolbar by means of the standard WPTools actions.