NFS ACLs does not work in Guestsystems

I have an problem with ACLs over NFS3 in Linux Guestsystems. The Problem is, when i mount a nfsshare from an KVMguest, the UnixACLs were not mapped too. I don’t know why. But this is only when i have the NFSshares on an virtulamachine. When i do the same with ein real machine, ACLs work well.
You can see that:

mount from physical machine:

touch data.txt rwrw--+ data.txt

mount from virtual machine:

touch data.txt rw-r-- data.txt

When a say “mount” on both. The ACL-flage is set. Strange, very strange.
I’ve tested this with Ubuntu 12.04 64bit and Gentoo 64bit.

I’ve testet this with anoter storageformat (qcow2, raw), with virtio, SATA.
I’ve testet the filesystems ext4 and jfs. Every time the same. I feel pretty helpless.

Thanks a lot for help