Cisco VPN :: Use Proxy Bypass On ASA 5510?

We have a custom web application which is heavily relying on javascript. We're trying to access it via the webportal but this application does not load correctly (it barely shows a white page).
 
the link is [URL] and SUBIF-ISP2 is the public interface facing the internet. This is the rule as displayed by the CLI:
 
proxy-bypass interface SUBIF-ISP2 path-mask oursubdirectory target [URL]
 
Despite having this command in place, nothing changes. I tried multiple combinations adding the xml and hostname rewrite or changing the interface but nothing, the page is the same like if this rule was not applied.