I don't quite understand why i'm getting this. before I had this field I got it. I made the field. set-accessbility for everyone. Some reason I still get this. I believe it's relative to the GotoWebinar integration.
If you have SFDC 'Professional' you need to add the IsAllDayEvent to the Activities -> Event Page Layout. It's not there by default and the directions here conveniently left that out (as of today).
If you have the one of the other versions, I believe you need to set the visibilty of that field to readable for your synch user/profile.
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