PopupMenu _BeforePopup event not fired all the times - MutliThreaded Application

Hi, I am using Synchfusion controls v 3.2.1.0. In our application, I have a form in which I have used XPMenus.PopupMenu. This form is called from multiple screens of the application. Also from other context menus and toolbar menus. Now there exists problem when this form is called from one particular sequence. PopupMenu _BeforePopup event is NOT fired i that sequence. I have checked form code. Execution steps are same as always the form entry point is one public method and input values are also same. On difference I think is threads. As our application is multi threaded, it is possible that each sequnce has a different thread. So, we are unable to identify how to identify problem. Can any one throw light on this? Rgds Rajani Kanth