trouble mounting a zip drive on parallel port

[Alex Walker]

Here's on of those things that should be simple but is giving me a 
surprising number of headachs...

I'm trying to mount a parallel zip drive on FreeBSD 4.8. I did re-configure 
my kernel to include the vpo driver and I get the following message on 
"dmesg":

vpo0: <Iomega VPI0 Parallel to SCSI interface> on
ppbus0
vpo0: EPP mode
vpo0: VP0 error/timeout (5)
vpo0: VP0 error/timeout (5)

The errors are a little worrying, but it does seem to be seeing the drive. 
Then, when trying to mount it, I get this error:

mount_msdos: /dev/da0s4: Device not configured

I'm sure there's something very small and simple that I'm doing wrong, and 
I'd be grateful if someone would kindly point it out.

Thanks a lot,
Alex