Hi Filipe,
The link you are using is based on version 6.3, in order to access the 6.4 based versions please use the following link:
http://samples64.visualwebgui.com/mainform.wgx
After v6.4RC1 is released we will change the main link to work with 6.4 as well.
HOWEVER: v6.3 worked perfectly with FireFox and IE so I really can't tell what's stopping it from showing. Do you get an error?
Kind Regards,
Itzik Spitzen