Ontask change activity is not firing in sharepoint visual studio workflow

Hi All.

I have developed visual studio workflow for creating multiple tasks for an item

but as per my requirement I need to programmatically update the tasks using another workflow.

when ever I update the status of task to "complete" the workflow is getting locked and ontaskchange event is not firing

http://msdn.microsoft.com/en-us/library/office/hh128696(v=office.14).aspx

I am using the same code from the above link and it is working fine when ever I do it manually and it is getting locked when I do it programmatically below is my sequence diagram

Sarath Sannadi Sharepoint Dev at Saksoft