A family of Microsoft presentation graphics products that offer tools for creating presentations and adding graphic effects like multimedia objects and special effects with text.
This will sometimes happen if the projector isn't very powerful, or if the brightnes and contrast have both been turned way up (usually in an effort to overcome the un-powerful-ness of the projector!). Try using the "reset" button to reset the projector back to factory settings -- or at least put it back to neutral brightness and contrast and see if the watermark shows up.
Alternatively, if you know it will be projected, make the watermark darker (assuming it's on a light background). It may look funny on your laptop, but it will look okay on the projector.
-- Echo [MS PPT MVP] http://www.echosvoice.com