NAS - See signature iMac - 10.7.2 MacMini - 10.6.7
TimeMachine *backups* seem to work fine for both computers. But I can only "Enter TimeMachine" on the 10.6.7 Mac. On the 10.7.2 Mac, it will mount the volume, but then thats it. I have noticed that when the Mini mounts the volume to backup I can navigate the spares bundle without issue. But when the iMac mounts the volume to backup, I can't navigate the sparse bundle due to "..not having the proper permissions.
I *think* I just fixed my problem. I went to the folder under Backups.backdb in finder and changed the Staff Permissions to Read/Write. Now the iMac will enter TM correctly and I backup *and* restore from previous backups.
