[thredds] a question about "forecastModelRunSingleCollection"

I am having problems with the "forecastModelRunSingleCollection" in thredds catalogs - this collection is based on netcdf files with names of the type 

FORDAILY_startyyyyMMdd_dumpyyyyMMdd.nc

Each file has a time axis of length 1. The dataset is set up like this:

<datasetFmrc name="Test scanfmrc 4" path="fmrc/test/4" >
   <metadata inherited="true">
      <timeCoverage>
         <start>2008-04-09</start>
         <end>2008-05-20</end>
      </timeCoverage>
   </metadata>
<netcdf xmlns="http://www.unidata.ucar.edu/namespaces/netcdf/ncml-2.2 " enhance="true"> 
      <aggregation dimName="runtime"
         type="forecastModelRunSingleCollection"
         timeUnitsChange="true" >
<scanFmrc location="/opt/local/share/java/tomcat5/content/ thredds/public/topaz/" 
            regExp=".*FORDAILY.*[0-9]{8}_.*\.nc"
            runDateMatcher="#_start#yyyyMMdd"
            forecastDateMatcher="#_dump#yyyyMMdd"/>
      </aggregation>
   </netcdf>
</datasetFmrc>

A collection of files such as this:

FORDAILY_start20080430_dump20080430.nc
FORDAILY_start20080430_dump20080501.nc
FORDAILY_start20080430_dump20080502.nc
FORDAILY_start20080430_dump20080503.nc
FORDAILY_start20080430_dump20080504.nc
FORDAILY_start20080430_dump20080505.nc
FORDAILY_start20080507_dump20080507.nc
FORDAILY_start20080507_dump20080508.nc
FORDAILY_start20080507_dump20080509.nc
FORDAILY_start20080507_dump20080510.nc
FORDAILY_start20080507_dump20080511.nc
FORDAILY_start20080507_dump20080512.nc

Gives me a 2D forecast time and runtime like this:
Dataset {
    Float64 valtime[runtime = 2][valtime = 6];
    String runtime[runtime = 2];
} fmrc/test/4/Test_scanfmrc_4_fmrc.ncd;
---------------------------------------------
valtime[2][6]
[0], 0.0, 24.0, 48.0, 72.0, 96.0, 120.0
[1], 168.0, 192.0, 216.0, 240.0, 264.0, 288.0
runtime[2]
"2008-04-30T00:00:00Z", "2008-05-07T00:00:00Z"
Seems like the offset is calculated relative to the first "start" date only? In addition the 2D forecast selection is the only one which actually gives a data set - all the others (best estimate, constant offset etc etc) present me with no opendap access link. I should also mention that the above datasetfmrc will fail if I remove the timecoverage metadata - then it seems to fail when extracting the daterange from the data set:
[16/May/2008:14:44:23] ERROR thredds.catalog.InvDatasetFmrc : Error making catalog for fmrc/test/4 
java.lang.NullPointerException
at ucar .nc2.thredds.MetadataExtractor.extractDateRange(MetadataExtractor.java: 251) at thredds.catalog.InvDatasetFmrc.makeCatalog(InvDatasetFmrc.java:302) at thredds.catalog.InvDatasetFmrc.makeCatalog(InvDatasetFmrc.java:151) at thredds .servlet.DataRootHandler.makeDynamicCatalog(DataRootHandler.java:1234) at thredds.servlet.DataRootHandler.getCatalog(DataRootHandler.java:1202) at thredds .servlet.DataRootHandler.processReqForCatalog(DataRootHandler.java:1117) 
        at thredds.servlet.CatalogServlet.doGet(CatalogServlet.java:78)
...


Any hints on how to fix this would be appreciated.


Best Regards,
Knut Lisæter