AMPSExcel.SubscriptionForm.updateControls C# (CSharp) Method

        private void updateControls()
        {
            if (!string.IsNullOrEmpty(cmbServer.Text) && !Globals.AMPSAddin.getWorkbookInfo(_workbook).Servers.ContainsKey(cmbServer.Text))
            {
                // server is now invalid
                cmbServer.Text = "";
            }
            if (txtName.Text != "" && cmbServer.Text != "" && cmbTopic.Text != ""
                && txtRange.Text != "")
            {
                btnOK.Enabled = true;
            }
            else
            {
                btnOK.Enabled = false;
            }
        }