Hello. I am working with ipsec tunnels more than 8 years (pix501, pix525, asa5505, asa5520, different cisco routers and mikrotiks). For checking the connectivity we should be sure that there nat is working ( or disabled by nat 0 command) for this networks . Also we should check the security levels of the interfaces and check access-lists. To make the new vpn connection we should make nat translation, build acl which point to the needed traffic to encrypt,create crypto map or add new rules into existing map and do almost the same things on the other side of ipsec tunnel. Need the 50% milestone to start work.
Cheers!