Do you have any form in your page? Are you using submit button to submit the request to the servlet?
Please read about request lifecycle.
[edited after googling around]
I tried to get some link on it for a while. But no success. So, just take this statement.
The JSP is generally the last component in the request chain. As Adeel mentioned, this is not the place to add things to a request object unless you are forwarding back to the servlet again before sending the output to the browser.