Hello,
Try to match Isakmp/Ipsec parameters on both sides.
First use simple /basic parameters to just bring up tunnel .Make sure you are able to ping the VPN peers .Check if there is no NAT/PAT device in between.
Phase 1
----------
authentication: pre-share
encryption: 3des
Hash: md5
DH group : group 2
Lifetime for phse 1 SA : 86400 seconds
Match the isakmp key both sides.
Phase 2:
------------
Transform set: ESP-3DES
Crypto ACL: mirror traffic
Life time for Phase 2 SA : 3600 seconds
Match above parameters for phase1 and phase 2 on both ends vpn devices.
Do not use optional parameters initially like PFS etc. Just try to bring up tunnel with only required parameters.
HTH
Saju