MongoDB convert standalone mongod to sharded replica set cluster
You have config server replica set installed?
You are running at least one mongoS -service
You are connecting (with mongo) to mongoS when you are working with cluster
You have added your replica set(s) to the cluster with sh.addShard() -command
You have added (at least one) your databases to cluster with command sh.enableSharding("yourDBname")


This point your collection is still there, sitting on original location with all data. You still need to shard your collections, which data is needed to "spread" to other shards (nodes).