SharePoint Worflow Extended Propoerties do not retain its value after the workflow task is changed

I am using SharePoint 2010 Workflow where i have created couple of Task Edit Forms in Infopaht 2010.

Here is the reference of how i am specifying extended property value in TaskEdit form from the SharePoint Workflow. Similar to the refrence article, In my TaskEdit Form also i have one Text box whose value i specified as extended property from my workflow.

My Problem is that once a workflow task is created the extended propery is properly displayed in the task edit form, but when the user changes the task that point onward if the user agains opens his assigned workflow task, the extended property value is not retained. It appears blank.

Here is开发者_JAVA百科 how I am specifying the extended property from my workflow's CreateTask activity.

    SPWorkflowTaskProperties wtp = new SPWorkflowTaskProperties();
    wtp.ExtendedProperties["ExtendedPropertyField"] = "Some text value";

Do i have to reset it somewhere on task changed event ? Am i missing something here ? Any idea ?

Thanks.

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Yes I think it should be reset/retained in the on task changed activity. Check if the field is retained during this event

public SPWorkflowTaskProperties onTaskChanged1_AfterProperties = new Microsoft.SharePoint.Workflow.SPWorkflowTaskProperties();
string field_value=onTaskChanged1_AfterProperties.ExtendedProperties["ExtendedPropertyField"].ToString();

field_value should not be null.

Thanks