dumping a collection using mongodump with option --out - gives an error.

Steps i took:

mongodump --db test -u username -p Password -h mymongodatabase.onthecloud:12888 -vvvvv --collection posts --out -

displays the error:
Wed Feb 29 21:48:13 creating new connection
to:mymongodatabase.onthecloud:12888
Wed Feb 29 21:48:13 BackgroundJob starting: ConnectBG
Wed Feb 29 21:48:13 connected connection!
connected to: mymongodatabase.onthecloud:12888
Wed Feb 29 21:48:13 nextSafe():

{ $err: "unauthorized db:test lock type:-1 client:10.3.55.10", code: 10057 }

Wed Feb 29 21:48:13 User Assertion: 13106:nextSafe():

{ $err: "unauthorized db:test lock type:-1 client:10.3.55.10", code: 10057 }

assertion: 13106 nextSafe():

{ $err: "unauthorized db:test lock type:-1 client:10.3.55.10", code: 10057 }

'

however when i remove '--out -', it will dump out the collection fine. I've tested this on 1.8.2 and the lastest version 2.0.3.

I also tested this on my local mongo which does not have authentication (testing it with the option '--out -') and that works fine. Im guessing somethings wrong with authentication?