VPN Coection: Draytek Vigor 2820 Caot Initiate IPSEC Tuel

I have been asked to setup a site-to-site IPSEC VPN Tuel from a Vigor 2820 (at the client's premises) to a Cisco ASA 5505 (hosted at Rackspace). I have input all of the details that Rackspace had provided and these have been double checked to confirm that they are the correct details however, I caot seem to initiate the tuel coection so the VPN does not currently work.

Along with the site-to-site coection, Rackspace have provided client-to-site licenses utilising the Cisco VPN Client. Outside of the client's premises, I am able to configure these client-to-site coections where I then ping the Rackspace local IP address and it retus data meaning that the VPN coection is initiated. However, whilst I am coected to the Vigor 2820, the client-to-site coection caot be initiated.

Therefore, I am wondering if the Vigor is blocking these VPN coections (both the site-to-site and client-to-site coections)? Any advise on this would be appreciated as I have spent several days trying to find a solution to get these coections to work. Also, the client is ruing Windows Small Business Server 2011 where most computers are networked to the server but even computers that are not networked, will not coect with the client-to-site VPN either.