mount_ext2fs : device not found

[Marc Hufschmitt]

  I've a IDE hard drive sliced in 4 part
ad0s1 : NTFS
ad0s2 : linux swap
ad0s3 : linux ext2fs
ad0s4[a-f] : ffs (FreeBSD 5.1)

mount_ntfs /dev/ad0s1 /mnt/XP  : It works.
mount_ext2fs /dev/ad0s3 /mnt/linux : /dev/ad0s3 not found (not the exact 
message)

Does someone have this bug with devfs and mount_ext2fs ?