Problem with setting up SNMP on fortigate

Hello, I have Fortigate 3100D I am trying to set up SNMP traffic sensor to monitor the virtual interfaces and physical one. 

I have problem with communicating with Fortigate I am trying to connect to it with MGMT interface with SNMP activated on it. 

PRTG sensor not able to get response from Fortigate SNMP. how i can pool all the interfaces in different Vdoms? 

Thank You in advanced