Taglib, hvorfor virker det bare ikke?

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

i toppen, herefter begyndet netbeans og den indbygget tomcat server, at tee sig helt vildt.

jeg prøvet en lille test:

                <c:when test="&{4 < 5}">
                    hej med dig
                </c:when>

på min jsp side.

result:

Stacktrace:
    org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:504)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:375)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
    org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:368)


root cause

org.apache.jasper.JasperException: The absolute uri: http://java.sun.com/jstl/core cannot be resolved in either web.xml or the jar files deployed with this application
    org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:510)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:375)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
    org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:368)
    org.apache.jasper.runtime.JspRuntimeLibrary.include(JspRuntimeLibrary.java:966)
    org.apache.jsp.index_jsp._jspService(index_jsp.java:42)
    org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:332)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
    org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:368)


root cause

org.apache.jasper.JasperException: The absolute uri: http://java.sun.com/jstl/core cannot be resolved in either web.xml or the jar files deployed with this application
    org.apache.jasper.compiler.DefaultErrorHandler.jspError(DefaultErrorHandler.java:50)
    org.apache.jasper.compiler.ErrorDispatcher.dispatch(ErrorDispatcher.java:407)
    org.apache.jasper.compiler.ErrorDispatcher.jspError(ErrorDispatcher.java:114)
    org.apache.jasper.compiler.TagLibraryInfoImpl.generateTLDLocation(TagLibraryInfoImpl.java:316)
    org.apache.jasper.compiler.TagLibraryInfoImpl.<init>(TagLibraryInfoImpl.java:147)
    org.apache.jasper.compiler.Parser.parseTaglibDirective(Parser.java:423)
    org.apache.jasper.compiler.Parser.parseDirective(Parser.java:492)
    org.apache.jasper.compiler.Parser.parseElements(Parser.java:1552)
    org.apache.jasper.compiler.Parser.parse(Parser.java:126)
    org.apache.jasper.compiler.ParserController.doParse(ParserController.java:211)
    org.apache.jasper.compiler.ParserController.parse(ParserController.java:100)
    org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:155)
    org.apache.jasper.compiler.Compiler.compile(Compiler.java:295)
    org.apache.jasper.compiler.Compiler.compile(Compiler.java:276)
    org.apache.jasper.compiler.Compiler.compile(Compiler.java:264)
    org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:563)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:303)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
    org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:368)
    org.apache.jasper.runtime.JspRuntimeLibrary.include(JspRuntimeLibrary.java:966)
    org.apache.jsp.index_jsp._jspService(index_jsp.java:42)
    org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:332)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
    org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:368)