imposs mount vg

Hello,
I can't mount my vg : what would be the fs id with the "mount" command ? (I've formatted one 12 GB partition with "8e" fs id, as a the vg, and created 4 lv in it ; all is OK, but mounting it, is impossible)

Thanks,
Adeline

ps : lvm 1.0.1 and Mandrake Linux 8.2

mount /dev/volumegroup/logicalvolumename /mnt

Also did you do a

vgscan
vgchange -a y

James