Error in MySql

I keep randomly encountering the following error:
Omeka has encountered an error

Zend_Db_Statement_Mysqli_Exception
Mysqli statement execute error : Column 'time' cannot be null

#0 /home/pkp3/akkadian.yctl.org/application/libraries/Zend/Db/Statement.php(303): Zend_Db_Statement_Mysqli->_execute(Array)
#1 /home/pkp3/akkadian.yctl.org/application/libraries/Zend/Db/Adapter/Abstract.php(480): Zend_Db_Statement->execute(Array)
#2 [internal function]: Zend_Db_Adapter_Abstract->query('INSERT INTO `om...', Array)
#3 /home/pkp3/akkadian.yctl.org/application/libraries/Omeka/Db.php(79): call_user_func_array(Array, Array)
#4 /home/pkp3/akkadian.yctl.org/application/libraries/Omeka/Db.php(252): Omeka_Db->__call('query', Array)
#5 /home/pkp3/akkadian.yctl.org/application/libraries/Omeka/Db.php(252): Omeka_Db->query('INSERT INTO `om...', Array)
#6 /home/pkp3/akkadian.yctl.org/application/libraries/Omeka/Record/AbstractRecord.php(543): Omeka_Db->insert('RecordsTags', Array)
#7 /home/pkp3/akkadian.yctl.org/application/models/Mixin/Tag.php(53): Omeka_Record_AbstractRecord->save()
#8 [internal function]: Mixin_Tag->afterSave(Array)
#9 /home/pkp3/akkadian.yctl.org/application/libraries/Omeka/Record/AbstractRecord.php(251): call_user_func_array(Array, Array)
#10 /home/pkp3/akkadian.yctl.org/application/libraries/Omeka/Record/AbstractRecord.php(280): Omeka_Record_AbstractRecord->delegateToMixins('afterSave', Array, true)
#11 /home/pkp3/akkadian.yctl.org/application/libraries/Omeka/Record/AbstractRecord.php(550): Omeka_Record_AbstractRecord->runCallbacks('afterSave', Array)
#12 /home/pkp3/akkadian.yctl.org/application/libraries/Omeka/Controller/AbstractActionController.php(175): Omeka_Record_AbstractRecord->save(false)
#13 /home/pkp3/akkadian.yctl.org/application/controllers/ItemsController.php(88): Omeka_Controller_AbstractActionController->editAction()
#14 /home/pkp3/akkadian.yctl.org/application/libraries/Zend/Controller/Action.php(516): ItemsController->editAction()
#15 /home/pkp3/akkadian.yctl.org/application/libraries/Zend/Controller/Dispatcher/Standard.php(308): Zend_Controller_Action->dispatch('editAction')
#16 /home/pkp3/akkadian.yctl.org/application/libraries/Zend/Controller/Front.php(954): Zend_Controller_Dispatcher_Standard->dispatch(Object(Zend_Controller_Request_Http), Object(Zend_Controller_Response_Http))
#17 /home/pkp3/akkadian.yctl.org/application/libraries/Zend/Application/Bootstrap/Bootstrap.php(97): Zend_Controller_Front->dispatch()
#18 /home/pkp3/akkadian.yctl.org/application/libraries/Zend/Application.php(366): Zend_Application_Bootstrap_Bootstrap->run()
#19 /home/pkp3/akkadian.yctl.org/application/libraries/Omeka/Application.php(79): Zend_Application->run()
#20 /home/pkp3/akkadian.yctl.org/admin/index.php(28): Omeka_Application->run()
#21 {main}

It will continue to give me the error then at some point work when I click save. Any suggestions?
Pam

What version of Omeka are you using? This sounds like something that was fixed a while ago.

Well, I used a one-click install on DreamHost and the version is 2.1.4 - which is a few .installs back. I'll look for documentation on upgrading. Thanks.