Mounting USB CD-ROM manually, after boot

[Steve Bertrand]

Hi everyone,

To get right to the chase, FBSD 7.0, I plug in an external USB CD-ROM 
device with a CD (of FreeBSD 7.0) and I want to mount it manually into 
the filesystem.

The device shows up with a label, and appears as /dev/cd0 (in dmesg).

# mount /dev/cd0 /cdrom

...fails, with a:

mount: /dev/cd0 : Invalid Argument

I have nothing else in /dev that would indicate any new device was 
attached. I know for fact the .iso is burned correctly, because I can 
boot from the same CD on another PC. Even still, a bad ISO burn still 
shouldn't prevent me from mounting AFAIK.

I've also tried all manner of cd0a etc, but they don't exist. (I can 
confirm cd0 is the only entry that appears in /dev after USB insertion).

Can anyone shed some quick light onto the solution that I am likely 
purely overlooking?

Thanks,

Steve