TCP 10.5 - PWSend event handler method sometimes not called

Migrateduser

We have customized process initiation form with following code behind

public partial class RequestForm : PowerWork.PWWebForms.PWFormPage{       /// <summary>    /// Page Load (before firing eventhandlers)    /// </summary>    /// <param name="sender"></param>    /// <param name="e"></param>    protected void Page_Load(object sender, System.EventArgs e)    {        ixtTCPWebHelper ixtTCP = new ixtTCPWebHelper(this);        ixtTCP.ixtPageLoadReqForm(this);           }    /// <summary>    /// Page sending    /// </summary>    /// <param name="sender"></param>    /// <param name="e"></param>    protected void Page_PWSending(object sender, System.EventArgs e)    {        logger.Info("Starting ixtPWprocessSend");       //hide lineitems       SetLineItemPanelVisibility(this, false);       //Initialize process instance       PWProcessInstance pwInst = new PWProcessInstance();       pwInst.SetField("_default.RealApproverID", " ");       pwInst.SetField("_default.RealApprover", "");       pwInst.SetField("_default.RealApproverEmail", "");              logger.InfoFormat("ixtPWprocessSend - instance {0} - initialized", pwInst.ProcessID);      IxtAddAttachmentControl ctrl_AddAttachment = (IxtAddAttachmentControl)page.FindControl("AddAttachmentControl");      if (ctrl_AddAttachment._fileUpload.HasFile)      {            PWClient.StopSend("Please upload selected attachment!");            return;      }        ...    }}

When the process is submitted the method Page_PWSending should be always called. It contains some important logic for the process. It is called most of the times. But occasionally (once a month), it is not called and process then ends in error state. So far we were unable to reproduce it.

Have somebode encoutered such behavior? Any recommendations?