NTA cannot receive sflow from Fortigate

Hi,

My fortigate 110C has version 5.0 build 147

NTA version 3.11

I configured to push flows from WAN interface of firewall to Solarwind, but in NTA it show up "never receive flow"

I install wireshark to monitor the NIC in Server and I can see the flows from Fortigate. Other netflow sources are OK.

I do a search, some said that the problem is in the OS ver 4.0, but mine is 5.0.

What wrong with me? Please give me some advices

Thanks a lot!!!