Executing custom command with Mongoid 3.1

Question

I'm trying to run custom javascript command under Mongoid 3.1

User.collection.database.session.cluster.with_primary do
    p User.collection.database.command(eval: 'function() { return 3+3; }')
end

And i have only this error:

Moped::Errors::ConnectionFailure: Could not connect to a primary node for replica set   <Moped::Cluster nodes=[<Moped::Node resolved_address="127.0.0.1:27017">, <Moped::Node resolved_address="127.0.0.1:27018">, <Moped::Node resolved_address="127.0.0.1:27019">]>