[eluser]Sarfaraz Soomro[/eluser]
try just the field name and the callback as the argument, don't know why you put the second argument as 'datecreated'
Code:
$this->form_validation->set_rules('datecreated','callback_date_check');
alternately you can try this syntax;
Code:
$this->form_validation->set_rules( array( 'datecreated' => 'callback_date_check' ) );