email function doesn't work well in 2.0.1

We are upgrade our system to 2.0.1 according to the document. The test in my local cumputer works fine, but email function doesn't work well in the system on the server. The application didn't stuck but no email was sent to administrator or user when user profile was updated. The message from tomcat log is following. Is there any one has same problem and any sugggestion to fix it?
Thanks,
Wei
Our system is consist of Postgres8.1 in Linux, Tomcat 5.20, Java 1.5.10 and Openclinica 2.0.1 in window server.
WARNING: found null object! 11
Apr 24, 2007 10:00:16 AM org.akaza.openclinica.dao.core.EntityDAO execute
WARNING: Exeception while executing dynamic statement, EntityDAO.execute: update user_account set user_name=?, passwd=?, first_name=?, last_name=?,
email=?, active_study=?, institutional_affiliation=?,
status_id=?, update_id=?, date_updated=now(), date_lastvisit=?,
passwd_timestamp=?, passwd_challenge_question=?,
passwd_challenge_answer=?, phone=?, user_type_id=?
where user_id=?: Unknown Types value.
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