http 500 internal server error

[looking]

java.lang.ClassCastException: javax.jdo.JDOUserException cannot be
cast to javax.servlet.ServletException
at org.apache.jasper.runtime.PageContextImpl.handlePageException
(PageContextImpl.java:754)
at org.apache.jsp.test1_jsp._jspService(test1_jsp.java:107)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:94)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:806)
at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:
487)
at org.mortbay.jetty.servlet.ServletHandler.handle
(ServletHandler.java:362)
...................




the above is the errors.
What happened?
How can I do?

[looking]

PersistenceManager pm = PMF.get().getPersistenceManager();
Query qPostings = pm.newQuery(Postings.class);

qPostings.setFilter("account_id == id");
qPostings.declareParameters("Integer id");

try {

List<Postings> res = (List<Postings>)qPostings.execute(5492);
if(res.iterator().hasNext()) {
for(Postings e : res) {
out.print(e.getAccountId() + "<br />");
}
}
else {
out.print("no results");
}

}
finally {
qPostings.closeAll();
}


this is the codes.