IPsec with Juniper - Could not find acceptable proposal

Hi, I have problem with Phase I. My fortigate is trying to establish tunnel with Juniper (which is ISP) on the other side, every parameter is ok on each side and I don't have any error in vpn event logs on fortigate. It even says that phase I status is success. But when I do packet capture from Fortigate I see message "Could not find acceptable proposal" and it is sent as informational message from Juniper to Fortigate. 

We have already made IPsec  tunnel with same parameters but  with Cisco and different remote IP. 

Does anyone have any idea what could it be?