How to enter empty field to date field with persistent field and DBEditbox

Hey!

Do anybody know solution to my problem? At first, I'm not allowed to change
table's settings. Situtation is that I have DBEditBox with persisten field
component. Field's type in table is date (paradox), so I used date-mask for
that control. Now, after playing around with values in that control I
deside to give no value at all. But, I just reseive error message, witch
demands a proper date value.

Literals (date dots) in inputmask must be saved too, because the date field
in table. But the date can't be empty neather (XX . XX . XX). Althought, it
would be nice, if user can enter empty value when wanted!

Kimmo