An error occurred while connecting to the remote speaker

Hi tech folks,
I am getting this error when I tried to connect iTunes with the remote speaker. The error message states that ‘An unknown error occurred’ How to fix this error? I confirmed it is running in the latest version firmware. Is there any configuration problem with iTunes? Please help me to fix this error. Thanks.

An error occurred while connecting to the remote speaker “Flairport”. An unknown error occurred (-15000).
