Radio Button Model returns undefined value when a save button is clicked

I have 2 radio buttons, which I assigned values of ‘0’ and ‘1’ respectively. I need to get the value when I click my Save Button but It returns an Undefined value. Here is my code. What could be my problem?

 <tr ng-repeat=" item in recruleData">
 <td>
                    {{item.package_name}}
                </td>
   <td> <input type="radio" name="radio" ng-model="radio.selectedProductBlock"
            value="0"  >A<br/>
    <input type="radio" name="radio" ng-model="radio.selectedProductBlock"
            value="1" > B
    </td>
    <a class="btn btn-primary pull-right" ng-click="radioValue();">Save</a>
</tr>

my JS Code

$scope.selectedProductBlock;
$scope.radioValue= function(){    
   alert($scope.selectedProductBlock);    
}

Source: AngularJS