got error using mongo / java.net.C​onnectExce​ption:

i used mongoDB from matlab. but i got error.

error log >>>

 Error using mongo (line 388)
 [Mongo Driver Error]:Timed out after 10000 ms while waiting to connect. Client view of cluster state is  {type=UNKNOWN, servers=[{address=localhost:27017, type=UNKNOWN, state=CONNECTING,
exception={com.mongodb.MongoSocketOpenException: Exception opening socket}, caused by    {java.net.ConnectException: Connection refused (Connection refused)}}].

 Error in mongoDB (line 5)
 conn = mongo(server,port,dbname)

my code

 server = "localhost";
 port = 27017;
 dbname = "AAA";
 conn = mongo(server,port,dbname)
 isopen(conn)

 employee1.employee = 26;
 employee1.department = 'Sales';
 employee1.salary = 100000;

 documents = employee1
 collection = "jse";
 n = insert(conn,collection,documents)
 close(conn)