R – session variable issue with user control in Son of smart part webpart

The user control is a search screen that consists of a gridview. I am string the filtered results of the gridview in a datatable and storing the datatable in the session. I am accessing the datatable in the session on the next postback.

The problem is that when I am storing the dattable in the session, even though the lines of code don't throw any exception, the web page shows "An unexpected error has occurred". I was able to track down the reason to be the assignment of the session variable with the help of remote debugging.

I had earlier tested the user control outside of sharepoint and checked that it worked perfectly in asp.net page.

I am using sharepoint 2007 and using VS 2008 for development, the framework being used is 2.0. I am very new to sharepoint development and any lead will be very helpful.