restoring records doesn't work for custom modules

You will get an error like this:

Please see a full discussion here: http://vtiger-crm.2324883.n4.nabble.com/Vtigercrm-developers-Cant-restore-records-from-custom-modules-td22546.html

To fix it I would change the $this->db = new PearDatabase() initialization in Vtiger_CRMEntity constructor to $this->db = PearDatabase::getInstance();.

This is Vtiger_CRMEntity's constructor: