Filters for all dates

Hey,

I am using Between and AND to filter the dates in report what I have specified in two testboxes in relevant form. Its working on that but if I leave the textboxes blank. How will I get all the dates. Its showing error. May be Null value.

Can anybody help me out.

I have more troubles in filters but let u know after I get the solution of this.

Best Regards

Jaidev Khatri