It looks like you are swaping the Variable and the columns

Based on your parameter and expected result.....

Declare

@DatumOd SmallDateTime

,@DatumDo SmallDateTime

Select

@DatumOd='20021201'

,@DatumDo='20021231'

Select *

From #T1

Where

( @DatumOD >= Datod And @DatumOD <= Datdo )

And

( @DatumDo >= Datod And @DatumDo <= Datdo )