I am not getting calender next to Date textbox

I created a reoport using wizard.In my quesry i took two date parameters.But when i run my report i get two texboxes StartDate and EndDate.How do i get calender button in front of the text boxes.Below is my query.



SELECT dbo.tblReferralTransferStatus.RefId
FROM dbo.tblReferralTransferStatus INNER JOIN
dbo.tblDownloadTracking ON dbo.tblReferralTransferStatus.VendorId = dbo.tblDownloadTracking.VendorId AND
dbo.tblReferralTransferStatus.DateModified < dbo.tblDownloadTracking.DateModified INNER JOIN
dbo.tblVENDOR ON dbo.tblReferralTransferStatus.VendorId = dbo.tblVENDOR.VendorId
WHERE (dbo.tblVENDOR.VendorName = @vendorname)AND (dbo.tblReferralTransferStatus.DateModified >= CAST(@StartDate AS varchar)) AND (dbo.tblReferralTransferStatus.DateModified < CAST(@EndDate AS varchar))