Please check that SMFShop code has been added to your Sources/Subs.php code. If not, find:
validateSession();
Add after:
// Begin SMFShop code
loadLanguage('Shop');
if (allowedTo('shop_admin'))
$context['admin_areas']['shop'] = array (
'title' => $txt['shop_admin'],
'areas' => array(
'shop_general' => '<a href="' . $scripturl . '?action=shop_general">' . $txt['shop_admin_general'] . '</a>',
'shop_items_edit' => '<a href="' . $scripturl . '?action=shop_items_edit">' . $txt['shop_admin_items_addedit'] . '</a>',
'shop_cat' => '<a href="' . $scripturl . '?action=shop_cat">' . $txt['shop_admin_cat'] . '</a>',
'shop_inventory' => '<a href="' . $scripturl . '?action=shop_inventory">' . $txt['shop_admin_inventory'] . '</a>',
'shop_restock' => '<a href="' . $scripturl . '?action=shop_restock">' . $txt['shop_admin_restock'] . '</a>',
'shop_usergroup' => '<a href="' . $scripturl . '?action=shop_usergroup">' . $txt['shop_admin_usergroup'] . '</a>',
)
);
// End SMFShop code