Vaadin reports "Session Expired" in Oracle WebLogic Server 11gR1 (10.3.5)

Vaadin 6 / 7 / 8
1

I test vaadin and WebLogic recently and find an interesting result:

  1. Use wizard of Vaadin 7 project to generate a project with target runtime server “Oracle WebLogic Server 11gR1 (10.3.5)”.
  2. Deploy the project, button “Click me” is displayed.
  3. If click the button, it reports Session Expired" although WebLogic TimeoutSecs is set to 3600s by default.
  4. Copy the code to a Vaadin 6 project, I get the same.

Because two projects run ok in Tomcat 7, Does any weblogic guru know the solution?