I am getting this error when i try to make a page type of Module under the HomePage, does anyone know why?

Error at line 1739 of /Applications/MAMP/htdocs/tron-sites/onboard/framework/model/DataObject.php

// HomePage
class HomePage extends Page
{
private static $has_many = array(
'ModulePages' => 'ModulePage',
'HomeSlides' => 'HomeSlides',
'ComingSoon' => 'ComingSoon'
);

private static $allowed_children = array(
'ModulePage',
);

//Getting CMS Fields For our Home slides DataObject
public function getCMSFields()
{
$fields = parent::getCMSFields();
$fields->addFieldToTab('Root.HomeSlides', GridField::create(
'HomeSlides',
'Slides On This Page',
$this->HomeSlides(),
GridFieldConfig_RecordEditor::create()
));
$fields->addFieldToTab('Root.ComingSoon', GridField::create(
'ComingSoon',
'Modules Coming Soon',
$this->ComingSoon(),
GridFieldConfig_RecordEditor::create()
));
return $fields;
}

}

class HomePage_Controller extends Page_Controller
{
public function init()
{
//Pull in parent properties for controller e.g css & js assets
parent::init();
Requirements::css($this->ThemeDir().'/css/homepage.css');
}

// Return all Members(use this on template to loop client logos)
function pullMembers(){
$members = DataObject::get('Member');
return $members;
}

}

// ModulePage
<?php
/**
* Created by PhpStorm.
* User: Heath
* Date: 6/01/16
* Time: 4:47 PM.
*/
class ModulePage extends Page
{
private static $db = array(
'iconClass' => 'Text',
);

private static $has_one = array(
'HomePage' => 'HomePage'
);

private static $has_many = array(
'ModuleVideos' => 'ModuleVideo',
'ModuleScreenshots' => 'ModuleScreenshot'
);

private static $can_be_root = false;

public function getCMSFields()
{
$fields = parent::getCMSFields();

$fields->addFieldToTab('Root.Main', TextField::create('iconClass', 'glyphicon class e.g glyphicon-home'), 'Content');

//MAIN ASSETS ADDED TO CMS
$fields->addFieldToTab('Root.Videos', GridField::create(
'Video',
'Videos on this page',
$this->ModuleVideos(),
GridFieldConfig_RecordEditor::create()
));

//Add Screenshot tutorials create tab to module page
//MAIN ASSETS ADDED TO CMS
$fields->addFieldToTab('Root.Screenshots', GridField::create(
'Screenshots',
'Screenshots for this Module',
$this->ModuleScreenshots(),
GridFieldConfig_RecordEditor::create()
));

return $fields;
}
}

class ModulePage_Controller extends Page_Controller
{
public function init()
{
//Pull in parent properties for controller e.g css & js assets
parent::init();
Requirements::css($this->ThemeDir().'/css/module-page.css');
}

/**
* @return string
*/
public function getScriptName()
{
//return 'job-details.js';
}

/**
* @return string
*/
public function getStyleName()
{
return 'module-page.css';
}

}