Idiom: Flogging a dead horse

Idiom Definitions for 'Flogging a dead horse'

If someone is trying to convince people to do or feel something without any hope of succeeding, they're flogging a dead horse. This is used when someone is trying to raise interest in an issue that no-one supports anymore; beating a dead horse will not make it do any more work.
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#0 /home/aking/app/lib/class.db_mysqli.php(406): UE_DB_Base->haltmsg('Error: %s\n')
#1 /home/aking/app/lib/class.db_mysqli.php(130): DB_MySQLi->halt('Error: %s\n', NULL)
#2 /home/aking/app/lib/class.db_base.php(21): DB_MySQLi->query('SELECT w.word\n\t...')
#3 /home/aking/app/lib/class.idiom.php(283): UE_DB_Base->query('SELECT w.word\n\t...')
#4 /home/aking/public_html/reference/idioms/idiom.php(157): UE_Idiom->get_similar_idioms()
#5 {main}