Starting with IBM Websphere MQ 7.1+, IBM’s changed default security model, so that usage of MQ admin user to access QM through client channels is disabled.
To connect to your v7.1+ Queue Managers in Qflex, it is necessary to create a new channel with MCA=’non admin user with rights’ or enable usage of MQ admin as it were in previous versions of Websphere MQ.
Please see both approaches illustrated here: http://www-01.ibm.com/