time machine sparsebundle in use

All,

When running a time machine backup from my MacBook Pro to the Time Machine service running on my Mountain Lion Server, I get a message that the sparsebundle is already in use.

The other 5 systems backing up the to the Time Machine Service are fine.

Apart from deleting the sparsebundle and redoing the whole backup, is there a way to tell Time Machine that the Sparsebundle is not in use?

Regards,

Gareth