Error restore vma.lzo

Hello,

I encounter an error when restoring a VMN (KVM):

root@virtuel:/mnt/pve/Backup_Pfsense/dump# qmrestore vzdump-qemu-100-2013_03_03-02_45_08.vma.lzo 100
tar: This does not look like a tar archive
tar: Skipping to next header
tar: Exiting with failure status due to previous errors
ERROR: archive contaions no data

Please help me.
I'm blocked

Thanks