I\'m not sure if this is actually possible, but I\'m essentially wanting a reverse of the \'&\' isolate scope in AngularJS. Here is a Plunkr to demonstrate.
Basicall
Here is a plunk that solves your current problem. I am not sure what you are attempting to do. But as far as I know, there is no way of calling something in the isolate scope from an external scope. Ofcourse, you could setup a two way bound variable between the isolate scope and the external scope, change the variable in the external scope and $watch for it on the isolate scope ( this will work like an eventing mechanism )... That is one way of doing what you are attempting to do.. if you insist on it.
Alternatively, there is a mechanism to call a function on the external scope from the isolate scope. Its kind of like a callback.
See this http://plnkr.co/edit/5MT4vo9qXtV6nQikfEiH?p=preview