Error: Procedure or function SP_AddEmp expects parameter @Emp_Gender which was not supplied

hi all

i have astored procedure to update table,im using radio option control gender to select gender:

the table as below :

emp_id int,

emp_name nvarchar(50)

emp_gender nchar(10)

and the stored procedure to update this table is as below :

ALTER proc [dbo].[SP_EditEmpDetails]
   @emp_id int,
   @emp_name nvarchar(50),
   @emp_gender nchar(10)
as
Begin
   update tbl_Employee set Emp_Name= @Emp_Name,Emp_Gender=Emp_Gender
   where emp_id=@emp_id
end

also 

in the page is like below :

 <table  class="auto-style1">
            <tr>
                <td class="auto-style2">Employee Full Name :</td>
                <td class="auto-style3">
                    <asp:TextBox ID="txtFullName" runat="server"></asp:TextBox>
                </td>
                <td class="auto-style3">
                    &nbsp;</td>
            </tr>
            <tr>
                <td class="auto-style2">Gender:</td>
                <td class="auto-style3">
                    <asp:RadioButton ID="rbMale" runat="server" Text="Male" GroupName="Gender" /></td>
                <td class="auto-style3">
                    <asp:RadioButton ID="rdFemale" runat="server" GroupName="Gender" Text="Female" /></td>
                <td>&nbsp;</td>
            </tr>

</table>

and the code behind the page is like below :

protected void btnEdit_Click(object sender, EventArgs e)
{
        Session["Grid_ID"] = gvEmpList.SelectedDataKey.Value;
       
        SqlCommand cmd = con.CreateCommand();
        cmd.CommandText = "SP_EditEmpDetails";
        cmd.CommandType = CommandType.StoredProcedure;


        cmd.Parameters.AddWithValue("@Emp_Name", txtFullName.Text);
        cmd.Parameters.AddWithValue("@Emp_ID", Convert.ToInt32(Session["Grid_ID"]));
        //cmd.Parameters.AddWithValue("@Emp_Gender", rbMale.Text);

        con.Open();
        SqlDataReader V = cmd.ExecuteReader();
        
        lblmsg.Text = "employee updated!!";

        con.Close();
}

how to handel the radio button in order to select and value go to the table ?

regards