Hello foudaatebaceles,
You can use the following debugs to be able to determine what is making the tunnel to fail:
- debug crypto condition peer ipv4 <peer ip address>
- debug crypto isakmp
- debug crypto ipsec
If you are failing at phase 2, most likely there's a mismatch with the interesting traffic or the transform set.
You might also want to check for any pfs configured.
Regards,
-Javier-