When you try to edit a rich-text field in Acrobat or Reader 9 with the properties toolbar in docked mode, the toolbar is dimmed or displays “No current selection.”
Undock the properties toolbar and use it in floating mode.
This issue occurs if the properties bar was already docked when you opened the document. If you open the properties toolbar and dock it after opening the document, then it works only for the current document. In Acrobat X and Reader X, it is no longer possible to dock the properties toolbar in the user interface, so this issue cannot occur there.