Angular ng-change for select not calling the declared method

I have the following html form select statement

<select ng-change="setBillGroup()" ng-model="bill.groupId" class="span8" ng-options="d.id as d.name for d in groups"></select>

and the js

myApp.controller('myAppController', function($scope, myAppService) {

.....
function setBillGroup(){
 console.log("setBillGroup method called!");
    ......
 }

....
});

But for some reason the setBillGroup() never seems to get called when I select something or the other in the form.