On click button event is not triggered in AngluarJS

In my AngularJS app, I want to pass input field's value to controller when button is clicked. What I am doing for that is posted below but it's not working. So please guide what is the issue?

index.html

<input type="text" ng-model="searchKey">
<button type="button" ng-click="loadSearch(searchKey)">Search</button>

myCtrl.js

app.controller('myCtrl', function($scope, $http) {
    function loadSearch(key) {
        alert(key);
    }
});

#angular.js