Exception with JSF in a portlet

[philippe aristote <philippe.aristote@xxxxxxxxxxxx>]

Hi,

i've developed a portlet (MemberManagement) using jsf pages to create a 
form. my portlet works correctly (except for the error messages precised 
in a previous topic), but an exception is thrown when the page 
containing the portlet is loaded.
this is the exception :

ApplicationDispatcher[/MemberManagement] "Servlet.service()" pour la 
servlet jsp a lancé une exception java.lang.ClassCastException
       at com.sun.faces.taglib.jsf_core.ViewTag.doEndTag(ViewTag.java:220)
       at 
org.apache.jsp.pages.registration.step1_jsp._jspx_meth_f_view_0(step1_jsp.java:129)
       at 
org.apache.jsp.pages.registration.step1_jsp._jspService(step1_jsp.java:86)
       at 
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:94)
       at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
       at 
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:324)
       at 
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
       at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
       at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
...

step1.jsp is the name of the jsf page included in the portlet.
this is not the end of the stack trace, it is much more longer...

thanks for any suggestion...

philippe