Fairlight-CMI

I don't know if anybody came accross to this problem:

On loading a System disk on my IIx I get the message: "Can't load 
midi". Does it mean that it can't find the midi interface or the 
System disk is too old? The System Disk I'm using is a Rev 4.0 and it 
says also Midi 68k on it.

Any help would be very much appreciated.

Best regards,

Sven