I have just constructed my first custom tag usin (jakarta-tomcat-3.2.3 using jdk1.3.1_01 on a 
windows platform). I have done all the things the very useful Professional JSP 2nd Editon has 
shown me, but and it's a big frustrating but, when I come to implement my custom tag in a JSP 
all I keep getting is the following error:

Error: 500

Location: /exper/genericDBtester.jsp

Internal Servlet Error:

org.apache.jasper.compiler.CompileException: 
C:\jakarta-tomcat-3.2.3\webapps\exper\genericDBtester.jsp(9,0) Unable to load class null
        at org.apache.jasper.compiler.TagBeginGenerator.init(TagBeginGenerator.java:129)
        at 
org.apache.jasper.compiler.JspParseEventListener$GeneratorWrapper.init(JspParseEventListe
ner.java:759)
        at 
org.apache.jasper.compiler.JspParseEventListener.addGenerator(JspParseEventListener.java:
138)
        at 
org.apache.jasper.compiler.JspParseEventListener.handleTagBegin(JspParseEventListener.jav
a:909)
        at 
org.apache.jasper.compiler.DelegatingListener.handleTagBegin(DelegatingListener.java:194)
        at org.apache.jasper.compiler.Parser$Tag.accept(Parser.java:813)
        at org.apache.jasper.compiler.Parser.parse(Parser.java:1077)
        at org.apache.jasper.compiler.Parser.parse(Parser.java:1042)
        at org.apache.jasper.compiler.Parser.parse(Parser.java:1038)
        at org.apache.jasper.compiler.Compiler.compile(Compiler.java:209)
        at org.apache.jasper.servlet.JspServlet.doLoadJSP(JspServlet.java:612)
        at org.apache.jasper.servlet.JasperLoader12.loadJSP(JasperLoader12.java:146)
        at org.apache.jasper.servlet.JspServlet.loadJSP(JspServlet.java:542)
        at 
org.apache.jasper.servlet.JspServlet$JspServletWrapper.loadIfNecessary(JspServlet.java:258)
        at org.apache.jasper.servlet.JspServlet$JspServletWrapper.service(JspServlet.java:268)
        at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:429)
        at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:500)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
        at org.apache.tomcat.core.ServletWrapper.doService(ServletWrapper.java:405)
        at org.apache.tomcat.core.Handler.service(Handler.java:287)
        at org.apache.tomcat.core.ServletWrapper.service(ServletWrapper.java:372)
        at org.apache.tomcat.core.ContextManager.internalService(ContextManager.java:812)
        at org.apache.tomcat.core.ContextManager.service(ContextManager.java:758)
        at 
org.apache.tomcat.service.http.HttpConnectionHandler.processConnection(HttpConnectionHan
dler.java:213)
        at org.apache.tomcat.service.TcpWorkerThread.runIt(PoolTcpEndpoint.java:416)
        at org.apache.tomcat.util.ThreadPool$ControlRunnable.run(ThreadPool.java:501)
        at  java.lang.Thread.run(Thread.java:484)

So please I am calling on all your technical know how to try and come to a solution to this 
problem.
Yours gratefully frustrated in London