I just installed 4.7 multiadd (on 1.3.8) and I get this error when I do a multiadd-

Code:
att: 26|24|25,63

Warning: Cannot modify header information - headers already sent by 
(output started at /home/jalansty/public_html/shop/admin
/products_with_attributes_stock.php:193) in /home/jalansty/public_html/shop/admin
/includes/functions/general.php on line 21
It adds the stock number fine. When I hit 'back', I can keep on working with any problems.

Any idea what is causing this?

Thanks-