Submitted this as a bug in game, but just in case it's WAI...
Picked up Virtuoso recently and was surprised to find that it doesn't work in conjunction with Suggestion. Every time I've tried it pop's up an error stating the target must be Fascinated first.
From the DDO Compendium Enthrallment
Expend a use of Bardic Music to enthrall multiple enemies. Enthralled enemies are fascinated until damaged, and suffer a -2 penalty to attack rolls and Will saves for 24 seconds plus 6 seconds per level, even after being disrupted from their reverie.
As the description specifically states Enthralled enemies are Fascinated I'd like to see the game reflect this. As it stands Virtuoso is considered the weakest of the PrE's by many. Having their improved Fascinate not work in conjunction with Suggestion seems just wrong.