the FAT partition must be created as (or converted to) primary, not 
extended/logical.
 It does not need to be the first partition however.

I believe the FAT partition is set to Primary... But how can I be sure?

You can use Windows Disk Management to determine this. By default (the colors 
are
customisable), dark blue indicates a primary partition and pure blue is logical
drives in an extended partition.  I am now questioning the availability of 
content in
a second primary partition formatted as FAT32, but don't intend to verify this 
in my
setup.

Same issue.  I have a Wii 4.1u using cIOS38_rev14 and FTPii 0.0.19. FTPii Won't 
mount
my USB hard drive.  All of my different USB loaders find my hard drive, Mplayer 
finds
hard my drive, GeexBox finds my hard drive.  THE ONLY THING NOT finding hard 
drive is
FTPii.

On the hard drive, the first partition is 350Gb WBFS.  2nd Partition is 120Gb 
Fat32
PRIMARY.  

I've read elsewhere that FTPii will only read the FAT32 partition if it is the 
1st
partition on the drive.  I sure hope that's not the only way this works.  Can 
anyone
confirm this or not?

I had this working- 500GB WD drive 1st= 240Gb WBFS, 2nd= 240Gb FAT32

It worked- though quite slow @ approx 200kb/s on a much more capable network- 
watch
internet tv 4x quicker streamed!

Then... it didn't work and also othe HB applications stopped recognising drive 
too. I
turned everything off pulled the USB out and reconnected and the HB 
applications work
but not the FTPii. Weird.

What version of ftpii are you using?
FTPii 0.0.19

What steps will reproduce the problem?
1. Start HBC
2. Start FTPii
3. Use "B" to Select USB Drive = Failed

What is the expected output? What do you see instead?
Unable to mount USB drive

Please provide any additional information below.
Can use drive with USBloader GX,WiiXplorer, MplayerCE etc, just not FTPii

Drive is a Seagate 500GB USB powered drive 

Forgot to add to above comment, drive is partitioned.
1st: WBFS 360GB - primary/active
2nd: 120GB Fat 32 - primary

read my post on issue 69. I changed the order of partitions. Fat32 1st primary 
partion 
and all worked fine.

Should be fixed in 0.0.20