Hello Everybody!
I'm a student come from  VietNam!
I'm studying about Richface framework and I'm using  A4J  library!
I had got a problem in JSF(Richfaces) Portlet when I used  A4J tag!
That problem is : When I run  the project about  JSF(Richfaces) portlet use A4J tag on JBoss Server into JBoss Tool of  Eclipse was ok!

But when I built it and made a war file, after I  run it on LiferayTomcat  Server, it throw a error!

If I didn't use  tag <a4j: />, it'd run ok!
Can anybody help me?
Thank you  very much!

This  is my error: