Masked Edit and date time field

Delphi 3.01  BDE 4.51  Access 97 DB.

When I use a mask on the TDBEdit control for a date field entry, I cannot
delete a date once one has been saved.  I get an 'invalid input Press
Esc...' message.  I have tried various variations of saving literals or not,
etc.  I would appreciate any advice on this.