Fortigate Sophos VPN ISAKMP SA still negotiating

Hello,

i have a Fortigate 500D with Firmware v.5.4.2 and i try to build a VPN-Tunnel to a Sophos UTM 9.

I have made a VPN-Tunnel to the Remote Address (IKE Gateway) from the Sophos Firewall.

When i make a

diag vpn ike log-filter name diag debug app ike -1 diag debug enable

i get following output:

IPsec SA connect 35 xx.xxx.xxx.x->xx.xxx.xx.xxx:0 using existing connection config found IPsec SA connect 35 xx.xxx.xxx.x->xx.xxx.xx.xxx:500 negotiating ISAKMP SA still negotiating, queuing quick-mode request

what does the still negotiating mean? Is this the error?

With Best Regards TobiasHan