Unexpected error occurred while communicating with Administration Service
I ran into the following issue when attempting to access Fast search features such as:
1. FAST Search keywords
2. Fast Search site promotion and demotion
I checked my Administrators group in the SP server. Fast Search ADMIN account configured is added in the Administrators group. Though I am unable to access these features.
Then found the resolution from a TechNet article.
1. Create a group named FASTSearchKeywordAdministrators in the SP server (this group is not automatically created during default installation).
Add the Fast Search ADMIN account (account configured for fast search) to this group.
Then tried accessing the features and everything works as expected.