Pie chart does not draw if id contains dot (like foo.com)

Here is my template:

``` xml

```

In my controller

``` javascript
$scope.piePoints = [{"Other domains": 70, "foo.com": 30, "bar.com": 100}];
$scope.pieColumns = [
{"id": "Other domains", "type": "pie"},
{"id": "foo.com", "type": "pie"},
{"id": "bar.com", "type": "pie"}
];
```

As a result, it draws only **Other domains** as 100%, since it does not see other entries. But it shows all three coulmns in the legend.