angular.js:9037 ReferenceError: $newPost is not defined

[sarit-lubu]

newPost isn't defined as a result ng-repeat='post in posts isn't working in main.html (see below).
i've defined everything exactly as you have described.
/mainController in chirpApp.js/
app.controller('mainController' , function($scope){
$scope.posts = [];
$scope.newPost = {created_by:'' ,text:'' ,created_at:'' };
$scope.post = function (){
$scope.newPost.created_at = Date.now();
$scope.posts.push($scope,$newPost);
$scope.newPost = {created_by:'' , text:'' ,created_at:''};
};
});

below is my html code in main.html