operational topology is not present

build: lithium rc0
installed features: odl-openflowplugin-flow-services-ui-li

steps to reploduce
1) connect mininet with any number of switches tot he controller
2) curl http://<IP>:8181/restconf/operational/network-topology:network-topology/topology/flow:1 -u admin:admin

{"errors":{"error":[

{"error-type":"application","error-tag":"data-missing","error-message":"Request could not be completed because the relevant data model content does not exist "}

]}