Fixed your link (missing : ) http://www.3m.com/product/informatio...-Fastener.html
Instructions sometimes say to let your adhesive set up (hours, or even overnight) before stressing the bond. I try to let the velcro sit for a while (after I attach it) before actually 'using' it. Also, if you don't go the Double Lock route, the smaller Mom & Pop True Value type hardware stores sometimes carry 'industrial strength" velcro.
I use a homemade wooden board, and sometimes I need to use a staplegun to beef up my velcro application.