Query Criteria From A Form...IsNull?

The below SQL gets it's criteria from a form but if the form has no Date1 and Date2 values I would like it to return all records.
I could not tinker it into submission. :confused:
Any pointers would be great.


SELECT [Central Western Region Database].[Date of Term], [Central Western Region Database].[Agent Number], [Central Western Region Database].[First Name], [Central Western Region Database].[Last Name], [Central Western Region Database].[District Name]
FROM [Central Western Region Database]
WHERE ((([Central Western Region Database].[Date of Term]) Between [Forms]![Compliance Lair Reporting]![Date1] And [Forms]![Compliance Lair Reporting]![Date2]) AND (([Central Western Region Database].Status)="inactive") AND (([Central Western Region Database].[Employee Type])="agent"))
ORDER BY [Central Western Region Database].[Date of Term];