Akai S1000 / S1100 samplers

Hi !

I have a SCSI Fujitsu MOD connected to my S-1100.

S-1100 & Fujitsu format and partition Verbatim Optical 230MB, 3.5" 
Optical Disk Rewritable 230MB flawlessly, but fails formatting and 
partitioning of

Verbatim Optical 640MB, 2048 Bytes/Sector 3.5" Rewritable media.

EMU E6400 does formatting and partitioning of this media and together w/ 
the Fujitsu,- so it�s not the drive not being able to recognize the 
640MB disks.

Any ideas why Akai S-1100 fails ?

I also use 1GB SCSI harddrives w/ the S-1100 and the S-1100 formats 
520MB of these and creates 40MB partitions,- so it�s able to recognize 
larger drives but only uses a portion.
I wonder why this isn�t the case w/ the 640MB MODs ...

thx in advance

PeWe