New hook not displaying in backoffice

[swalker]

I'm trying to create a new hook for the cart block module. I have made my cart module default to collapse and want to place it in my cartSpacer div, so when you click expand, the design expands as well (see screen shot composite) I have added and new ps_hook in my database(see screen shot)

I have added the following line to my header.tpl file:

{$HOOK_CART_SPACER} //new hook

I have added the following line to my header.php file:

$smarty->assign(array(
'HOOK_HEADER' => Module::hookExec('header'),
'HOOK_LEFT_COLUMN' => Module::hookExec('leftColumn'),
'HOOK_TOP' => Module::hookExec('top'),
'HOOK_CART_SPACER' => Module::hookExec('cartSpacer'), //new
'HOOK_NAV_BAR' => Module::hookExec('navBar'),
'static_token' => Tools::getToken(false),
'token' => Tools::getToken()
));

My hook still does not display as an option in the backoffice when I try to transplant my Cart block. I'm not sure what else I need to do. Any suggestions would be appreciated!

~Shannon