Material select is not enabled on button click

I have a material select which binds the data using angular, on page load I disabled the Material select, on button click am enabling the material select.

Issue : Material Select is not enabled

<body ng-app="materializeApp" ng-controller="BodyController">

<main>
    <div class="row container">
        <div class="col s12 m12 l12">
            <div class="card blue-grey darken-1">
                <div class="card-content white-text">
                    <span class="card-title">Update Form</span>
                    <div class="row">
                        <form class="col s12">
                            <div class="row">
                                <div class="input-field col s6">
                                    <input id="icon_prefix" type="text" class="validate" ng-model="data.firstname">
                                    <label for="icon_prefix">First Name</label>
                                </div>
                                <div class="input-field col s6">

                                    <input id="icon_telephone" type="text" class="validate" ng-model="data.lastname">
                                    <label for="icon_telephone">Last Name</label>
                                </div>
                                <div class="input-field col s8">
                                    <input id="email" type="email" class="validate" ng-model="data.email">
                                    <label for="email" data-error="Wrong" data-success="Right">Email</label>
                                </div>
                                <div class="section col s4">
                                    <div input-field>
                                        <select ng-model="projects.value" material-select ng-disabled="checked">
                                            <option ng-repeat="value in projects.choices">{{value}}</option>
                                        </select>
                                    </div>
                                </div>
                            </div>
                        </form>
                    </div>
                </div>
                <div class="card-action white-text right-align">
                    <a class="waves-effect waves-light btn" ng-click="edit()"><i class="material-icons right">cloud</i>Edit</a>
                </div>
            </div>
        </div>
    </div>
</main>

<script>
    var app = angular.module('materializeApp', ['ui.materialize'
        .controller('BodyController', ["$scope", function ($scope) {
            $scope.projects = {
                value: "Select Value",
                choices: ["p1", "p2", "p3", "p4"]
            };

            debugger;
            $scope.checked = true;
            $scope.edit = function () {
                $scope.checked = false;
            }

        }]);
</script>

krescruz / angular-materialize

Material select is not enabled on button click #213