TIme Machine on network drive
To map a network drive as a backup destination for TM is necessary to set the following parameter (I have Leopard on my Macbook):
defaults write com.apple.systempreferences TMShowUnsupportedNetworkVolumes 1
After that a strange behavior happens. I connected the afp share, mounted the Image file (Sparse File) and when I tried to do a full backup the system responded with an error (I didn't remember what was). The strange thing is that the day after the systems automagically start to work correctly. Time Machine mounted the afp disk, mounted the image disk and begin the backup. 6 hour laster the first full backup was done (via utp cable). Now each hour via wifi my backup start automatically.