Hi,
First off, you need make sure that the configuration on both the devices match. Please look at the interesting traffic carefully.
If does not help, please post the ASA config and screen shots of the Concentrator. The pages that we need screen shots for are :
Configuration > Tunneling and Security > IPSEC > LAN-LAN
configuration > Policy Management > Traffic Management > SA
I would also appreciate if you can send me the logs of the concentrator and the ASA.
Please do post if it helps.
Regards,
Kamal