FGT Conflict IP address On Fortigate

Hi All,

I have problem with my fortigate i'm Using fgt 90D firmware 5.6.2

I am configure mac address reservation on DHCP,Unknown Mac address set Block

It works, until i need to add new record of reservation Ip, my Laptop  that can't get IP because IP conflict I see in DHCP monitor,appears the IPaddress with same Mac address with my laptop,but my Laptop doesn't  get IP because conflict

I try to diagnose using 'diagnose debug application dhcps -1' but no messages appears

I use IP scanner tolls, there is so many IP belongs on fortigate

Please advice 

Thanks Qodri