The Datebook I know of is a commercial product with this web site:
A Tech Support link is there to answer your question.
I turned on my Tungsten E this morning to discover all my appts are hidden. Now whenever I turn on the PDA, all appts/To Do's are hidden and I have to hit the S in the top left corner to show them. I have no idea what I did to change this and can't find it in preferences to make them show. HELP!