Have you looked at your web.xml file in your application.
I hope the below information will resolve your problem.
http://faq.javaranch.com/java/SetupJstlForJsp2
How do I declare the web.xml file for
Servlets 2.5 and JSP 2.1? (Tomcat 6.0.14 and so on)
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
<display-name>web app name here</display-name>
<!-- rest of declarations go here -->
</web-app>
How do I declare the web.xml file for Servlets 2.4 and JSP 2.0? (Tomcat 5, Resin 3, and so on)
<web-app xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"
version="2.4">
<display-name>web app name here</display-name>
<!-- rest of declarations go here -->
</web-app>