mongoDb replication initialize replication -

i have error on mongodb replication . when try create configuration file:

config = {_id : 'replicatset1' , members : [{_id : 0 , host : 'localhost:15000'}, {_id : 1 , host : 'localhost:15001'} , {_id : 2 , host : 'localhost:15002'} ]}; 

this error got when try initiate replication :

{     "ok" : 0,     "errmsg" : "couldn't initiate : set name not match set name host localhost:15001 expects" 

}