Redirect causing blank screen error cakephp - cakephp

Question

$this->redirect called from any controller method seems to result in a blank screen error, despite turning debug to 2 in my core.php.
In my AdminAppController, located in App/Plugin/Admin/Controller, was this piece of code originally, in my beforefilter():
public function beforeFilter() {
parent::beforeFilter ();
$rusername = $this->Auth->user ( "Username" );
if ($rusername != "admin") {
$this->redirect ( "/" );
return;
}
This results was an admin wide blank screen error, regardless of username. By commenting out the redirect, it allowed me to enter the admin area again.
However, now whenever I use $this->redirect I get blank screen errors.
For example here is my Prices view through my Product controller:
<?php echo $this->Session->flash('flash');?>
<?php echo $this->Form->create('Product', array('action' => 'change')); ?>
<fieldset>
<h3>Products</h3>
<table>
<?php
foreach($products as $k=>$v){
echo $this->Form->hidden("Product.{$k}.id", array('value'=> $v["Product"]['id']));
echo $this->Form->input("Product.{$k}.name", array('value' => $v["Product"]["name"], 'disabled' =>'disabled'));
echo $this->Form->hidden("Product.{$k}.slug", array('value'=>$v["Product"]['slug']));
echo $this->Form->hidden("Product.{$k}.description", array('value'=>$v["Product"]['description']));
echo $this->Form->hidden("Product.{$k}.cateID", array('value'=>$v["Product"]['cateID']));
echo $this->Form->input("Product.{$k}.price", array('value' => $v["Product"]['price']));
echo $this->Form->hidden("Product.{$k}.photo", array('value'=>$v["Product"]['photo']));
echo $this->Form->hidden("Product.{$k}.photo_dir", array('value'=>$v["Product"]['photo_dir']));
echo $this->Form->hidden("Product.{$k}.active", array('value'=>$v["Product"]['active']));
echo $this->Form->hidden("Product.{$k}.views", array('value'=>$v["Product"]['views']));
echo $this->Form->hidden("Product.{$k}.created", array('value'=>$v["Product"]['created']));
echo $this->Form->hidden("Product.{$k}.modified", array('value'=>$v["Product"]['modified']));
}
?>
</table>
</fieldset>
<?php echo $this->Form->end(__('Submit')); ?>
My Products controller contains this method:
public function prices(){
$products = $this->Product->find ("all");
$this->set ("products", $products );
}
And this method is called from this view:
public function change(){
//create() resets model, precaution
$this->Product->create();
$data = $this->request->data;
$this->Product->saveMany($data['Product']);
$this->Session->setFlash( "Prices Saved.");
$this->redirect ( '/' );
return;
}
On submitting a change of price (which does save and alter the database, the redirect line causes the screen to go blank, with no errors, or any other indication of what has gone wrong.
Error logs show no sign of what is happening.
Thanks.

Answer 1

Apologies for the late Answer.
After much struggle it turned out to simple.
AdminAppController included some whitespace before an opening