Unable to read pop up messages in Mainframe Rumba application

Scenario: Not able to read the pop messages

Steps to reproduce:

Current Behavior: Unable to read the pop messages which comes in Rumba mainframe, which is the one needs to be validated

Expected Behavior:

Studio/Robot/Orchestrator Version:2016.2.6402

Last stable behavior:
Last stable version:
OS Version:
Others if Relevant: (workflow, logs, .net version, service pack, etc):