Drop down not load from db

Question

Dropdown class 

  public void LoadSelectBenefitsAndDeductionsCombo(ref DropDownList dgv)

        {

            // Code Part :6b

            //'***** Author: Mohammed Shamsheer

            //'*****  Date : 16/08/2013

            //'***** This function used to Load BenefitsAndDeductionsCombo  in web

            DataSet ds = new DataSet();

            object[,] ParmArray;

            ParmArray = new object[,] {

                {"@BranchID",BranchID}

                };

            ds = DB.ExecuteQuery_SP("SelectBenefitsAndDeductionsCombo", ParmArray);

            if (ds.Tables.Count > 0)

            {

                dgv.DataSource = ds.Tables[0];

                dgv.DataBind();

            }

        } 

------------------------------

Query for load dropdown

:

ALTER PROCEDURE [dbo].[SelectBenefitsAndDeductionsCombo]

(

@BranchID bigint

)

AS

SELECT BenefitDeductionID,BenefitDeductionName  FROM BenefitsAndDeductions WHERE BranchID=@BranchID

----------------------------------------

code behind for load drop down but itis showing 

 BenefitsAndDeductions obj = new BenefitsAndDeductions();

            obj.LoadSelectBenefitsAndDeductionsCombo(ref ddlBenefitsAndDeductionsType);

but it is showing