ZFS cannot promote out of space

Hi - wonder if someone can help with an issue I've got when I ran an ludelete command on one of our T4-1's running Solaris 10. I'd wanted to delete an old boot environment from a running server but it output the following:

root@tdukwbdb04:~ 274$ ludelete RPS-2013.11.20

cannot promote 'rpool/export/zones/tdukwbdbz04': out of space

cannot destroy 'rpool/export/zones/tdukwbdbz04-RPS-2013.11.20': filesystem has dependent clones

use '-R' to destroy the following datasets:

rpool/export/zones/tdukwbdbz04

Updating boot environment configuration database.

Updating boot environment description database on all BEs.

Updating all boot environment configuration databases.