LACP Problem in Fortigate 200D

[mahesh_secure]

Dear Team

For 3 days i am having a problem with Fortigate 200D LACP configuration.

I have configured LACP between Fortigate 200D and Dlink L2 switch.

please check the below configuration

Dlink LACP settings 

Mode-->static

Speed-->slow

algorithm-->L2

port 9 and 10

Fortigate 200D settings

Mode-->static

speed-->slow

Lacp-Ha-Mode-->disable

algorithm-->L2

Port 11 and 12

when fortigate port 11 is down all the traffic going through port 12. but when reconnect the port 11 its not coming up still port 11 is down. also the same status when disconnect the port 12. 

i am using fortios v5.0.12

Please help me to fix this asap. [&:]

Regards

Mahesh