Forticlient VPN Tunnel Gateway Authentication error

Hello

I have just configured a forticlient vpn tunnel for my remote user for accessing Internal Network, but when i try to connect the fortclient i am getting Gateway Authentication error, this is happening when i am using AES -128 and higher encrytipions with sha-256.

For 3des encryption and sha1 everything looks fine, here is my firmware version Fortigate 200D v5.0, build0292.

Please help.

Thanks

Ahmed