Hi Pawan,
I think this is a bug. Via our support contract we filed a bug, I did never get an answer from them. In my humble opinion the program logic switches to service control for Windows system by default and there is no choices. For Unix program control is used.
What I did at the end of the day, I entered the name of Hyperic's own Tomcat service into the input field. I was able to overcome the restriction that this field must not be empty. The price is that control of my own Tomcat by Hyperic should never be used in the GUI as it will shutdown the Hyperic server. But for me it was fine because as I already stated I will not use the Hyperic control dialogs.
Looks to me that any other service name might be fine as well to overcome the dialog.
Maybe this is an acceptable approach for you, too.
Cheers
Thorsten