SSG140 SNMP over Internet

Hi,

I've been trying to configure Snmp on ssg140 over public/Internet to monitor on SolarWinds server.

Got this message on ssg 'SNMP request from an unknown SNMP community aaa at X.X.X.X:xxxx has been received.'
But SolarWinds server failed to poll anything from the router, seems the request not thru or the router not allows the request.
Is it possible to do this over Internet? Or did I miss something?
Any help would be appreciated.
Thanks.