Glad it helped. You need to enable the Interface for ISAKMP to bring the tunnel up. You can check the configuration guide for more info. http://www.cisco.com/c/en/us/td/docs/security/asa/asa72/configuration/guide/conf_gd/ike.html
Have you enabled ISAKMP on the interfaces ?.. Cisco 1821:interface Serial0/0/0:0crypto isakmp enable Cisco 1921:interface GigabitEthernet0/0crypto isakmp enable
If it is stuck at MM_WAIT_MSG2, it usually means the other side is not responding. Check to see if they have reachability and also that ISAKMP is enabled (i.e. crypto isakmp enable)