Page Arguments Not Getting Passed
I would change your code to (as @J.Reynolds specified):

  $items['admin/commerce/inventory/%/%/%/%'] = array(
    'title' =&gt; 'Inventory',
    'description' =&gt; 'View inventory reports for your store.',
    'access arguments' =&gt; array('access commerce reports'), // Inherited by children.
    'page callback' =&gt; 'inventory_reports_dashboard',
    'page arguments' =&gt; array(3,4,5,6),     // page_arguments = threshold amount,  sort direction, hide zero inventory, email report to, save_to_email bool, download_csv
    'file' =&gt; 'inventory.dashboard.inc',
    'weight' =&gt; 0,
  );