MongoDB replicaSet keep 'syncing to' and only can be connect with shell

Hi I am new with MongoDB 2.6 Replica Set

I have three DB service in Docker and DB work in Replica Set

It works great I can connect to DB Read,Write in C#,MongoVUE

but I didn't know why my db will not be connect

I only can use mongo shell to connect DB

and use rs.status() show replica Set status

and that secondary DBs same status

lastHeartbeatMessage : 'syncing to: NowPrimaryDBAddress' 

and I destroy these docker service and restart everything work great again.

If I didn't destroy docker service it won't be able to connect in C#,MongoVUE

It happened the same situation that MongoDB not in a docker.

In three different ubuntu VM.

Is there any Log I can trace?

Or my Replica Set config wrong.