Connection between flowvisor and mininet

I have mininet virtual machine. I have flowvisor in another ubuntu virtual machine. They are not communicate with each other. In mininet when I use remote controller it is saying "Unable to contact the remote controller at 127.0.0.1:6633". After running flowvisor when I use this line "fvctl-xml --url=https://localhost:8081 addFlowSpace any 10 nw_dst=10.0.0.255/32 Slice:mySlice2=7"
It shows connection refused. Please help me.