In reply to naveensv:
If you are reversing the connection it will not work. On the transaction level each component plays a specific role, some of them can initiate actions and others not. In the case of the sequencer/driver connection only the driver can initaiate an action.
If you want to reverse the action you have to use different base class component for sequencer, i.e. uvm_push_sequencer. And you are using different ports and exports like this
m_sequencer.req_port.connect(m_driver.req_export);