When I open a showModalDialog in jsp, all properties related to actionform in my action was null value, for example

in jsp:
in javascript:
void showView()
{
window.showModalDialog("mAction.do?method=preView&dialogHeight:200px; dialogWidth:800px;dialogLeft:300...");
}

.....
<html:form action="mAction.do" method="post" ...>
</html:form>


in action:
public ActionForward preView(....)
{
MyActionForm myForm= (MyActionForm )form;
myForm.get("myproperty") is null !
....
}

and I could not read any values from jsp in action.