what is the CLI rejection saying exactly?

Cisco (config)#Crypto isakmp key sbcs address aaa.dyndns.org

                                                                                     ^

% Invalid input detected at '^' marker.

When I try a host name instead of ip address  the system says invalid input .The host name which I posted is not  a real hostname (just an example).If I put my real hostname also the result is the same.

Try Hostname parameter instead?

SBCS-Mobility(config)#crypto isakmp key ?
  0     Specifies an UNENCRYPTED password will follow
  6     Specifies an ENCRYPTED password will follow
  WORD  The UNENCRYPTED (cleartext) user password

SBCS-Mobility(config)#crypto isakmp key key123 ?
  address   define shared key with IP address
  hostname  define shared key with hostname

SBCS-Mobility(config)#crypto isakmp key key123

CISCO(config)#crypto map multisite 1 ipsec-isakmp
% NOTE: This new crypto map will remain disabled until a peer
        and a valid access list have been configured.
CISCO(config-crypto-map)#

Please advise me which acl i have to define her

You can normalize your config by following the steps in his app note as well:

https://supportforums.cisco.com/docs/DOC-9692

Esentially, the same on as Steve's.

Thanks,

Marcos