vTiger blank page when trying to save any entity - php

Question

I am currently in the process of creating new modules on vTiger 6.5. Currently I have been creating the modules using the vTlib, registering handlers ect.. All has been working well until I suddenly was unable to save any information on any modules even the standard modules.
I started a fresh install and went through the steps of installing my modules, I created one module fine but when registering the handler below I was then unable to save anything and just lead to index.php
<?php
require_once('include/database/PearDatabase.php');
include_once('include/events/include.inc');
$adb = PearDatabase::getInstance();
$em = new VTEventsManager($adb);
$module = 'AddIsa';
$em->registerHandler('vtiger.entity.beforesave', 'modules/'.$module.'/'.$module.'Handler.php', $module.'Handler');
$em->registerHandler('vtiger.entity.beforesave.modifiable', 'modules/'.$module.'/'.$module.'Handler.php', $module.'Handler');
$em->registerHandler('vtiger.entity.beforesave.final', 'modules/'.$module.'/'.$module.'Handler.php', $module.'Handler');
$em->registerHandler('vtiger.entity.aftersave', 'modules/'.$module.'/'.$module.'Handler.php', $module.'Handler');
echo 'Events Added Successfully.';
?>
UPDATE
I went to the table vtiger_eventhandlers and deleted the event handlers relating to my custom module and now it works fine. I cannot see why this would happen as I have previously registered event handlers using the same script which are also in this table.
Any ideas?

Answer 1

Please use vtiger Package Structure. Also if you are using event handler in your module. you must create event handler file and use Vtiger Module Event Structure

Answer 2

event handlers registered will be executed for all modules. Your script might have some error, That's why you can not save to any module. In your handler script you can check current module and skip executing further code like this
$moduleName = $entityData->getModuleName();
if ($moduleName != 'Invoice') {
return;
}