No Alert or Popup On Chat Request

Version - 7.0.4

I am debugging my site before I finally launch it, and another problem crept in.  When an online user tries to chat with another online user, there is NO notification of any sort to the recipient.

How are they suppose to know when someone wants to chat, when nothing happens at their end?  I can't find a resolve to this anywhere.

Thanks

hello can you specify what chat do you use :
1. Simple messenger
2. IM - messenger?