Kaltura_Client_Exception thrown

Invalid KS "MWRhNTFlM2I0MDFhNTRiODZlNDVjZmJjNWJhZjNhMzdmMjJhMjM0M3wxMDE7OzE0OTg3MjI1Mjk7MjsxNDk4NjM2MTI5LjY2NDM7QW5vbnltb3VzO2VkaXQ6Kg==", Error "-1,INVALID_STR"