Album track ordering not working

When you go into the Neuros Audio -> Albums view and select an album, the tracks
listed are not sorted according to the "tracknumber" tag in the ogg files. 
Instead, they appear to be sorted alphabetically.

This is not the case for MP3 files--in this view, the MP3 files are sorted
according to the track number tag.

My ogg files are encoded by Grip, which is basically a wrapper for oggenc.  The
command-line Grip uses for oggenc is:
oggenc -o %m -q 5 -a %a -l %d -t %n -N %t %w

...where %t is the track number specified by Grip.  The resulting ogg file looks
like this, according to ogginfo (note that the track number has a '0' in front,
ie "01", "02", "03"...not sure if that is significant):

New logical stream (#1, serial: 15d5825f): type vorbis
Vorbis headers parsed for stream 1, information follows...
Version: 0
Vendor: Xiphophorus libVorbis I 20011231 (1.0 rc3)
Channels: 2
Rate: 44100

Nominal bitrate: 160.032000 kb/s
Upper bitrate not set
Lower bitrate not set
User comments section follows...
        title=The Next Big Thing
        artist=Jesus Jones
        album=Already
        tracknumber=01
Vorbis stream 1:
        Total data length: 4385538 bytes
        Playback length: 4m:01s
        Average bitrate: 145.040392 kbps
Logical stream 1 ended