Want to display data from single parameter even Multiple Parameter Exists

Hi,

- Created two parameters(@District and @Region) which Iam passing inside created dataset which is below. Parameters "Allows multiple values" selection. @District and

@Region parameters has two different datasets with distinct values.

select * from node where District=@District andRegion=@Region

- drop tablix on report and configured with the above dataset. 
 
- I can able to see the data on tablix when i select both of the parameters(@District and @Region).

- Report producing error when i am selecting only "Region" values(Please select a value from the parameter 'select district') and also when selecting

"Districit"(Please select a value from the parameter 'select Region')

- Please let me know to view the data only any one of the parameter selected(even though there are multiple parameters exist).

Thanks.

Best Regards
Kashif