'Object reference not set to an instance of an object' Error observed only when i publish to IIS? I can run in my codebase successfully?

Hi,

   I have a functionality that on click of context menu we have option 'Export to PDF' and it will download to my local machine.

  This functionality will work fine when i run through code base. If i publish the same code and run in IIS i will  get alert message as 'object reference not set to an instance of an object'.

Please let me know any changes required w.r.t IIS7

Thanks in Advance

Regards

Rakesh B