Hello TT, This afternoon I confirmed that this is a bug (or a "feature") of the DateTimePicker control. I've replaced the control with a text box and am writing my own date validation routines, which will eliminate the problem. Pity... the DateTimePicker is certainly a more elegant and more attractive solution if it only worked properly. Thanks, Ron Friday, August 13, 2004, 6:25:06 PM, you wrote: T> I'm not a .NET porgrammer, but maybe you need to clear something (a storage T> field or whatever) before recalculating the new date. Maybe a register (?) T> is full. For a web-based membership management utility and information on list policies, please see http://nibec.com/24hoursupport/ To unsubscribe, send a blank email to 24hoursupport-request@xxxxxxxxxxxxx with "unsubscribe" (without quotes) in the subject.