I am trying to kick off the callback panel when a textbox looses focus but whenever the event is fired I get undefined or null for the return value of the textbox.value.  Here is the code:

<dxe:ASPxTextBox ID="DriverCodeTxt" runat="server" Width="170px"
            ClientInstanceName="DriverCodeTxt" EnableClientSideAPI="True">
            <ClientSideEvents LostFocus="function(s, e) {
  var targetElement = document.getElementById('DriverCodeTxt');
  CallbackPanel.PerformCallback(targetElement.getAttribute('Value')); // I've also tried targetElement.value which returns undefined
}" />
        </dxe:ASPxTextBox>
        <dxcp:ASPxCallbackPanel ID="CallbackPanel" runat="server" Height="87px" Width="782px"
            ClientInstanceName="CallbackPanel" OnCallback="CallbackPanel_Callback">
            <PanelCollection>
                <dxrp:PanelContent runat="server">
                    <asp:Label ID="Label3" runat="server" Text="Security Question: "></asp:Label><asp:Label
                        ID="QuestionLbl" runat="server" Text=""></asp:Label><br />
                    <asp:Label ID="Label2" runat="server" Text="Answer: "></asp:Label>
                    <asp:TextBox ID="AnswerTxt" runat="server" Width="380px"></asp:TextBox><br />
                    <br />
                    <asp:Button ID="SubmitBtn" runat="server" Text="Submit" />
                </dxrp:PanelContent>
            </PanelCollection>
        </dxcp:ASPxCallbackPanel>

protected void  CallbackPanel_Callback(object source, DevExpress.Web.ASPxClasses.CallbackEventArgsBase e)
    {
        SqlConnection sqlCnn = new SqlConnection(ConfigurationManager.ConnectionStrings["driverportalConnectionString2"].ConnectionString);

        sqlCnn.Open();
        SqlCommand sqlCmd = new SqlCommand();
        sqlCmd.Connection = sqlCnn;

        if (DriverCodeTxt.Text.Length > 0)
        {
            sqlCmd.CommandText = "select * from [Security] where [User] = '" + e.Parameter.ToString().ToUpper() + "'";
            sqlRdr = sqlCmd.ExecuteReader();

            if (sqlRdr.HasRows)
            {
                QuestionLbl.Text = sqlRdr["Question"].ToString();
            }
            else
            {
                lblStatus.Text = "User doesn't exist.";
            }
        }
    }

Hello David,

You should replace the following code

var targetElement = document.getElementById('DriverCodeTxt');
CallbackPanel.PerformCallback(targetElement.getAttribute('Value'));

with

CallbackPanel.PerformCallback(DriverCodeTxt.GetValue());