a plugin problem

[cqkerry]

I learned to write a plugin from 
url:http://wiki.apache.org/nutch/WritingPluginExample,
but i had made a different:i did not made a gew plugin,I just make some changes 
in parse-html.
first,i make four java classes,just like the example.
then in the plugin.xml i add:
<plugin id="parse-html" name="Html Parse Plug-in" version="1.0.0"
    provider-name="nutch.org">
   
    <runtime>
        <library name="parse-html.jar">
            <export name="*"/>
        </library>
        <library name="tagsoup-1.0rc3.jar"/>
    </runtime>
   
    <requires>
        <import plugin="nutch-extensionpoints"/>
        <import plugin="lib-nekohtml"/>
    </requires>
    <extension id="org.apache.nutch.parse.keyword.KeywordParser" name="Keyword 
Parser"
        point="org.apache.nutch.parse.HtmlParseFilter">
        <implementation id="KeywordParser"
            class="org.apache.nutch.parse.keyword.KeywordParser"/>
    </extension>
   
    <extension id="org.apache.nutch.parse.keyword.ParseKeywordIndexer"
        name="Parse keyword filter"
        point="org.apache.nutch.indexer.IndexingFilter">
        <implementation id="ParseKeywordIndexer"
            class="org.apache.nutch.parse.keyword.ParseKeywordIndexer"/>
    </extension>
   
    <extension id="org.apache.nutch.parse.keyword.ParseKeywordQueryFilter"
        name="Keyword Search Query Filter"
        point="org.apache.nutch.searcher.QueryFilter">
        <implementation id="ParseKeywordQueryFilter"
            class="org.apache.nutch.parse.keyword.ParseKeywordQueryFilter"
            fields="DEFAULT"/>
    </extension>   
   
    <extension id="org.apache.nutch.parse.html" name="HtmlParse"
        point="org.apache.nutch.parse.Parser">
       
        <implementation id="org.apache.nutch.parse.html.HtmlParser"
            class="org.apache.nutch.parse.html.HtmlParser">
            <parameter name="contentType" value="text/html"/>
            <parameter name="pathSuffix" value=""/>
        </implementation>
    </extension>
</plugin>
but when i run the plugin,i found KeywordParser did not have effect,just had 
JSParseFilter no KeywordParser
maybe i had missed some things or write wrong in the plugin,someone may help me!