I have not checked Eclipse, but at least three other HU-manufacturers products, and you might find what you are looking for in your manual, but what I've seen so far, and can remember is that you have to use any of FAT 8/16/32 formats. Some HUs even put a maximum number of folders and songs in folders etc, etc. I hope you will get it sorted out, it is so frustrating when "simple" things doesn'w work as you would have expected.
I did not like my crappy reply, so I went to the Eclipse web pages and found the following:
About playable USB memory standards
Supported File System: FAT 12/16/32
Playable Audio Format: MP3/WMA
Max.Current: 500mA
Compatibility: USB1.1/2.0
Correspondence: USB mass storage class
Playable MP3 file standardsSupported standards:
MPEG-1
MPEG-2
MPEG-2.5
Audio Layer III
Supported sampling frequencies:
MPEG-1:32, 44.1 (kHz)
MPEG-2:16, 22.05, 24 (kHz)
MPEG-2.5:8, 11.025, 12 (kHz)
Supported bit rate:
MPEG-1: 32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 288, 320 (kbps)
MPEG-2: 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 160 (kbps)
MPEG-2.5: 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 160 (kbps)
*1 Supports VBR. (8~320 kbps)
*2 Does not support free format.
Supported channel modes:
monaural, stereo, joint, dual
Playable WMA file standardsSupported standards:
WMA Ver. 7
WMA Ver. 8
WMA Ver. 9
Supported sampling frequencies:
8, 11.025, 12, 22.05, 32, 44.1 (kHz)
Supported bit rate:
8, 16, 24, 32, 40, 48, 64, 80, 96, 128, 160, 192 (kbps)
*1 Supports VBR (40~95 kbps)
*2 Does not play DRM.
Supported channel modes:
monaural, stereo
Format of USB memoryThe USB memory format must be ISO9660 Level 1 or Level 2.
Standards are as follows:
Maximum directory layers:
8 layers
Maximum characters for folder names/file names:
128 (including “.” and 3 letter file extension)
Allowable characters for folder names/file names:
A~Z, 0~9, _ (underscore)
Number of files possible on a single USB memory:
3000
Total number of folders possible on a single USB memory:
999
Maximum folders this main unit can recognize:
1000*
*1 A root directory is counted as one folder.
There is an image that I cannot copy, you will find an example how to set up your stick here:
http://www.eclipse-web.com/download/manual/cd7200mkII_e/audio/contents/1636.html