How can I get this to execute?
<p>I have a series of input sources which I want to use to execute a stored procedure on my sql database.  The stored procedure looks like this: </p>

<pre><code>USE [InvoiceSHC]
GO
/****** Object:  StoredProcedure [dbo].[UpdateSHCInvoice]    Script Date: 02/21/2013 12:03:58 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
-- =============================================
-- Author:      &lt;Author,,Name&gt;
-- Create date: &lt;Create Date,,&gt;
-- Description: &lt;Description,,&gt;
-- =============================================
ALTER PROCEDURE [dbo].[UpdateSHCInvoice] 
    -- Add the parameters for the stored procedure here
    @Ref nvarchar(50), 
    @PhaseName nvarchar(50),
    @PageType nvarchar(50),
    @Page float,
    @Percent nvarchar(50),
    @ChngType nvarchar(50),
    @RowCount int output
AS
BEGIN
    -- SET NOCOUNT ON added to prevent extra result sets from
    -- interfering with SELECT statements.
    SET NOCOUNT ON;

    -- Insert statements for procedure here
    insert into MasterData2 ([Ad],[Phase],[Page Type] , [Page Rate], [Percent] , [Change Type] )
                    values(@Ref, @PhaseName , @PageType , @Page , @Percent ,@ChngType );

    /* @@ROWCOUNT returns the number of rows that are affected by the last statement. */
    select @RowCount = @@ROWCOUNT 
END
</code></pre>

<p>I have a button on my form that prompts the user to update the table.  This is the code for it:</p>

<pre><code>using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;
using System.Data.SqlClient;



namespace WebApplication1
{
    public partial class _Default : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {

        }

        protected void GridView1_SelectedIndexChanged(object sender, EventArgs e)
        {

        }

        protected void MasterData_Selecting(object sender, SqlDataSourceSelectingEventArgs e)
        {

        }

        protected void btnUpdate_Click(object sender, EventArgs e)
        {

            SqlConnection con = new SqlConnection("server=(local);database=InvoiceSHC;Trusted_Connection=Yes");



            SqlDataAdapter DA = new SqlDataAdapter("UpdateSHCInvoice", con);

            SqlCommand cmd = new SqlCommand("UpdateSHCInvoice", con);
            cmd.CommandType = CommandType.StoredProcedure;

            SqlParameter Ref = cmd.Parameters.Add("@Ref", SqlDbType.NVarChar, 50);
            SqlParameter Phase = cmd.Parameters.Add("@Phase", SqlDbType.NVarChar, 50);
            SqlParameter PageType = cmd.Parameters.Add("@PageType", SqlDbType.NVarChar, 50);
            SqlParameter Page = cmd.Parameters.Add("@Page", SqlDbType.NVarChar, 50);
            SqlParameter Percent = cmd.Parameters.Add("@Percent", SqlDbType.Float );
            SqlParameter ChngType = cmd.Parameters.Add("@ChngType", SqlDbType.NVarChar, 50);

            Ref.Value = dlRef.SelectedItem;
            Phase.Value = dlPhase.SelectedItem;
            PageType.Value = dlPageType.SelectedItem;
            Page.Value = tbPage.Text;
            Percent.Value = dlPercent.SelectedItem;
            ChngType.Value = dlChngType.SelectedItem;


            con.Open();
            cmd.ExecuteNonQuery();




        }


    }
}
</code></pre>

<p>When I take out the cmd.ExecuteNonQuery() I get no error and also no results.  When I have that in there the result is an error System.InvalidCastException: Object must implement IConvertible.</p>

<p>I apologize in advance for my ignorance, I am self taught and learning something new everyday.  In approximately 127 years and 4 days I may be able to understand this.</p>
