JSTL if tag for equal strings

Try:

<c:if test = "${ansokanInfo.PSystem == 'NAT'}">

JSP/Servlet 2.4 (I think that's the version number) doesn't support method calls in EL and only support properties. The latest servlet containers do support method calls (ie Tomcat 7).

<c:if test="${ansokanInfo.pSystem eq 'NAT'}">