Some errors and how to write config file

[ouzensang]

Hi,
I use JanusGraph 0.3.2 and its build-in cassandra, my Gremlin version is 3.3.3, then I install opencypher 1.0.4 using gremlin console. I have loaded some data to JanusGraph. Then I input commands following https://github.com/opencypher/cypher-for-gremlin/tree/master/tinkerpop/cypher-gremlin-console-plugin

Then it returns error "scala.Predef$.refArrayOps([Ljava/lang/Object;)[Ljava/lang/Object;"
So I have some questions:

1. Before I input cypher queries, whether I need to open one specific graph using its properties config, like conf/janusgraph-cassandra.properties. Because I find conf/remote-objects.yaml does not mention which graph they query.
2. If we don't need to open one graph, then how can I solve the error "scala.Predef$.refArrayOps([Ljava/lang/Object;)[Ljava/lang/Object;"
3. I uninstall cypher-gremlin-console-plugin 1.0.4, then install 0.9.13. I re-run the above commands, and get error "java.lang.RuntimeException: java.util.concurrent.TimeoutException: Timed out while waiting for an available host - check the client configuration and connectivity to the server if this message persists".
   

I am very confused about these questions and looking forward your early reply :)