Looks like there is 2 problems you might encounter:
1)
https://github.com/strongloop/loopback/pull/1131 You might want to wait for a new loopback release to get it to work.
2) and if you use the mongo connector, newrelic doesnt support the native js mongo driver of version >= 2.0 now. Although they may in a few weeks so they say. Although I can see they just released a new version that: "Updated instrumentation for MongoDB to support previously un-instrumented
methods for 1.x and 2.x versions of the node-mongodb-native driver."
Let me know how it goes :)