Mapping fields in SOLR for faceting

Question

I'm indexing rich text documents into SOLR 3.4 using ExtractingRequestHandler and I'm having trouble getting it to behave like I want it to.

I would like to store creation date as a field to use for faceted search later and have defined the following in schema.xml:

<field name="creation_date" type="date" indexed="true" stored="true"/>

I index like this:

curl -s "http://localhost:8983/solr/update/extract?literal.id=myid&resource.name=myfile.xls&commit=true" -F myfile=@/path/to/myfile.xls

I get the dynamic field attr_creation_date (that other rules make sure), but I don't get it as creation_date. I have also unsuccessfully tried to use copyField like so:

<copyField source="attr_creation_date" dest="creation_date"/>

Yet another try was putting this in solrconfig.xml, but no luck:

<str name="fmap.Creation-Date">creation_date</str>

I'm pretty sure I'm missing something basic here. Any help is most appreciated!

Settings for ExtractingRequestHandler in solrconfig.xml:

<requestHandler name="/update/extract" startup="lazy" 
    class="solr.extraction.ExtractingRequestHandler" >
    <lst name="defaults">

        <str name="fmap.content">text</str>
        <str name="fmap.Last-Save-Date">last_save_date</str>
        <str name="fmap.Creation-Date">creation_date</str>
        <str name="fmap.Content-Type">content_type</str>
        <str name="lowernames">true</str>
        <str name="uprefix">attr_</str>

        <str name="captureAttr">true</str>
        <str name="fmap.a">links</str>
    </lst>
</requestHandler>

My schema.xml file (lots of default stuff): https://gist.github.com/1358002