Roller Installation

Hi
     I am trying to install roller(4.01) on ubuntu 9.04.  As soon as I
deploy roller I am getting this error

Unexpected Exception  Status Code 500  Message javax.servlet.ServletException:
java.lang.IllegalStateException: Roller Weblogger has not been bootstrapped
yet  Type
 Exception Roller has encountered and logged an unexpected exception.
can you tell me what may have caused this error?

Thanks
arvind