JSTL URI problem

I am using Tomcat 5.5.20, J2SE 1.4. I am not able to run JSTL program. It
is showing the error

*org.apache.jasper.JasperException: The absolute uri:
http://java.sun.com/JSP/jstl/core cannot be resolved
in either web.xml or the jar files deployed with this application
*
I have given taglib directive as follows in my JSP.

<%@ taglib prefix="c" uri="http://java.sun.com/JSP/jstl/core" %>

I have copied jstl.jar, standard.jar files from "jsp-examples"
application to my application's lib directory. Please give me any
clues.

When JSP is changed to jsp (small letters) it is working. But the url is
working with capital letters