Forms Data Controls :: Binding Two Dropdownlist And Featching Some Value From Database Through Stored Procedure

here I am binding two dropdownlist and featching some value from database through stored procedure

below is my sp

ALTER PROCEDURE [dbo].[Get_OpenCostCode]
-- Add the parameters for the stored procedure here
(@UserId NVARCHAR(50)) [Code]....

and here is the .cs code

[Code]....]

but wen i run this shows error,There is already an open DataReader associated with this Command which must be closed first.

I also put in my connectionstring tag in webconfig file MultipleActiveResultSets=true;