Event activities have to wait for try/catch

Hello,
My problem is, hopefully, a simple one. I have a label and picturebox that need to be visible when a button_click event occurs. The event includes a try/catch statement (for a SQL stored procedure) and that is what these items are for (to show the user that the process is running). The problem is that these items won't display until the try/catch is completed. I've tried moving them within the event code, using a delegate, goto statement etc... and the behaviour is the same. Any ideas would be much appreciated!

Here is the code:

private void button1_Click(object sender, EventArgs e)
        {          

            label9.Visible = true; // show "Vendor Contract Uploading" label
            pictureBox2.Visible = true; // show progressbar.gif
            button1.Visible = false; // hide "Execute Vendor Contract Upload" button
         
            try
            {           
            String vendorNo = dataGridView1.SelectedRows[0].Cells[0].Value.ToString(); // get Vendor_No
            SqlConnection conn = new SqlConnection(appString.ToString()); // SQL connection string from app settings
            SqlCommand command = new SqlCommand("A_P_VENDOR_CONTRACT", conn); // stored procedure
            command.CommandTimeout = 5000;
            command.CommandType = CommandType.StoredProcedure;
            command.Parameters.Add("@VENDOR_NO", SqlDbType.NVarChar).Value = vendorNo; // SP parameter
            conn.Open();
            int rows = command.ExecuteNonQuery();
            conn.Close();
            MessageBox.Show("Upload Completed!"); // operation completed message
            button3.Visible = true; // show "Upload .XLS File" button again
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }