UTM9 => Checkpoint IPSec S2S VPN

Hi,
I established an IPSec Site2Site VPN between our UTM and a Checkpoint Firewall.
Both sides are using networks (not hosts) to be encrypted.
local: 10.33.86.0/24 <=> remote: 172.20.250.0/24
The tunnel works, I can reach IPs in remote network 172.20.250.0/24
but the remote network can't reach IP's in my local network 10.33.86.0/24

This is the corresponding error message:

2013:01:03-18:14:38 fw-1 pluto[24905]: "S2S_1" #12: cannot respond to IPsec SA request because no connection is known for 10.33.86.5/32===***.***.x.2[***.***.***.2]...***.***.***.4[***.***.***.4]===172.20.250.10/32
2013:01:03-18:14:38 fw-1 pluto[24905]: "SS2S_1" #12: sending encrypted notification INVALID_ID_INFORMATION to ***.***.***.4:500

To work around this issue I added the host 10.33.86.5/32 to our local networks and 172.20.250.10/32 to the remote networks. As result, all IPs in 10.33.86.0/24 were reachable from remote side.
We compared everything 10 times. Tunnels between 2 Astaro UTMs are working as expected.
Does anybody have an idea about this?
Cheers
Thomas