IDV and NcML aggregation

IDV gang,

I tried using IDV with NcML for the first time, trying to aggregate two data sets along the time dimension (which is the actually called "ocean_time" in the netcdf file)

The data source comes up, but no Fields are displayed.

Here's my NcML:

<?xml version="1.0" encoding="UTF-8"?>
<netcdf xmlns=""; xmlns:xsi=""; xsi:schemaLocation="";>
<aggregation dimName="ocean_time" type="joinExisting"/>
<netcdf uri=""/> <netcdf uri=""/>

My question:
Is this an IDV problem or a problem with how I formulated the NcML?

And could I have figured this out myself? (Is there a way to validate NcML?)

Richard P. Signell
U.S. Geological Survey       Phone: (508) 457-2229
384 Woods Hole Road          Fax:   (508) 457-2310
Woods Hole, MA  02543-1598