drop down list checked

I had Drop down list which execute code when specific condition and I tried to check it through selected value but it get error

 protected void DDLProductFamily_SelectedIndexChanged(object sender, EventArgs e)
    {
        if (DDLProductFamily.Items.FindByText("Name").Selected == true)
        using (SqlConnection Con = Connection.GetConnection())
        {
            SqlCommand Com = new SqlCommand("GetListViewByProductCategory", Con);
            Com.CommandType = CommandType.StoredProcedure;
            Com.Parameters.Add(Parameter.NewInt("@ProductCategory_Id", DDLProductFamily.SelectedValue.ToString()));
            SqlDataAdapter DA = new SqlDataAdapter(Com);
            DA.Fill(dt);
            DataList1.DataSource = dt;
            DataList1.DataBind();
        }
        else if (DDLProductFamily.Items.FindByText("ProductFamilly").Selected == true)
        {
            using (SqlConnection Con = Connection.GetConnection())
        {
            SqlCommand Com = new SqlCommand("GetListViewByProductFamily", Con);
  开发者_Python百科          Com.CommandType = CommandType.StoredProcedure;
            Com.Parameters.Add(Parameter.NewInt("@ProductFamily_Id", DDLProductFamily.SelectedValue.ToString()));
            SqlDataAdapter DA = new SqlDataAdapter(Com);
            DA.Fill(dt);
            DataList1.DataSource = dt;
            DataList1.DataBind();
        }
        }
    }

Have you instantiate your dt object?

ProductFamily is spelled wrong ( 2 l's instead of 1) so you're getting a null reference:

else if (DDLProductFamily.Items.FindByText("ProductFamilly").Selected == true)

You might need to check the ListeItemCollection method FindByText.

DDLProductFamily.Items.FindByText("Name").Selected

DDLProductFamily.Items.FindByText("ProductFamilly").Selected

If an item is not found in the collection using the "Name" or "ProductFamilly" criteria, null is returned. So if you call "Selected" on a null object, it will throw a null reference exception.