'co_person_id' cannot be null on add

2012-02-22 13:53:04 Error: [PDOException] SQLSTATE[23000]: Integrity constraint violation: 1048 Column 'co_person_id' cannot be null
#0 /Applications/MAMP/htdocs/gears/trunk/lib/Cake/Model/Datasource/DboSource.php(436): PDOStatement->execute(Array)
#1 /Applications/MAMP/htdocs/gears/trunk/lib/Cake/Model/Datasource/DboSource.php(403): DboSource->_execute('INSERT INTO `cm...', Array)
#2 /Applications/MAMP/htdocs/gears/trunk/lib/Cake/Model/Datasource/DboSource.php(967): DboSource->execute('INSERT INTO `cm...')
#3 /Applications/MAMP/htdocs/gears/trunk/lib/Cake/Model/Model.php(1646): DboSource->create(Object(CoNsfDemographic), Array, Array)
#4 /Applications/MAMP/htdocs/gears/trunk/lib/Cake/Model/Model.php(2071): Model->save(Array, Array)
#5 /Applications/MAMP/htdocs/gears/trunk/lib/Cake/Model/Model.php(1908): Model->saveAssociated(Array, Array)
#6 /Applications/MAMP/htdocs/gears/trunk/app/Controller/StandardController.php(80): Model->saveAll(Array)
#7 /Applications/MAMP/htdocs/gears/trunk/app/Controller/CoNsfDemographicsController.php(154): StandardController->add()
#8 [internal function]: CoNsfDemographicsController->add()
#9 /Applications/MAMP/htdocs/gears/trunk/lib/Cake/Controller/Controller.php(473): ReflectionMethod->invokeArgs(Object(CoNsfDemographicsController), Array)
#10 /Applications/MAMP/htdocs/gears/trunk/lib/Cake/Routing/Dispatcher.php(104): Controller->invokeAction(Object(CakeRequest))
#11 /Applications/MAMP/htdocs/gears/trunk/lib/Cake/Routing/Dispatcher.php(86): Dispatcher->_invoke(Object(CoNsfDemographicsController), Object(CakeRequest), Object(CakeResponse))
#12 /Applications/MAMP/htdocs/gears/trunk/app/webroot/index.php(96): Dispatcher->dispatch(Object(CakeRequest), Object(CakeResponse))
#13