This issue was because of the access which i was given for my application. If you open DevTest and click on the padlock at the left bottom, then a "Security Permission Tab" opens. Here for me, it was:
User ID = *******
Role 1:Guest
------Permissions------
Start DevTest Workstation
View a Suite
View a Test Case
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Instead, the Role 1 should be "SV Power", which was granted to me by the Enterprise team.
Thanks for all you valuable suggestions.