MinimServer doesn't recognise expansion HD on MELCO N1Z/2

[uodal]

I connected an external HD (1TB) to the USB expansion slot of the Melco. The HD is formatted as NTFS. It's USB 2.0

The property 'contentDir' ist set to:
/mnt/disk1/share
/mnt/expansion1/Expansion
/mnt/expansion2/Expansion2

According to the Melco-NAS an expansion disc is connected, but has only 2 GB.

Windows Explorer does only show the following subdirectories:

N-3043 (the Melco NAS' name in my home network)
∟Expansion
..........∟ $RECYCLE.BIN
..........∟ .twonky
∟Internal
..........∟ ... (subdirectories A - Z)
∟Logs

I restarted and rescanned the MinimServer several times.

Any idea, how I can include the songs on the expansion disc into my music library? Maybe the disc should not be formatted as NTFS?

Thanks in advance!