Optional Report Parameters

Is there a way to create optional parameters in Reporting. For example, I have two tables Region and Country, with drop downs in report displaying the list of each. The stored proc for Country list expects an input parameter RegionID but does NOT require one for the result set to be fetched. The stored procs run fine in sql, but when run with the report, the designer always complains that the RegionID Parameter must be provided for the Country DataSet/List to be populated. Is there a way to create this RegionID parameter as optional such that the country list is populated with all rows in the Country table if no RegionId is provided, and filters if a RegionId is provided??



here is some code that I am using my stored procs





Code Snippet
For Regions
SP1
Create Proc... spGetRegions
Begin...




Select RegionID, RegionName From Region

Order By RegionName
End








Code Snippet

For Countries

SP2

Create Procedure dbo.spGetCountries

@RegionID int = NULL,

AS

Begin

Select CountryID, CountryName From Country C

WHERE C.RegionID = CASE WHEN @RegionID is null THEN C.RegionID ELSE

@RegionID END

ORDER BY C.CountryName

END