So you have a control on the form that's bound to a date field in the forms recordsoucre (ModifiedDate?). You update this control in the forms before update event, and it doesn't work? What does it do?
Be carefull with field and control names, .LastModified is a property of the recordset, and shouldn't be used as neither field nor control name.
What errormessages are you getting?
Roy-Vidar