global name 'APNApplication' is not defined Error

[Dealers]

I am using the Scarface Framework and getting this error: global name 'APNApplication' is not defined. The code is:

def register(self, request, pk=None):  
    """
    registers the device to sns
    :param your_device_instance: the device
    :param token: the push token or the registration id
    """
    device = self.get_object()
    token = device.token
    # get the correct notification plattform
    application_plattform = APNApplication()
   # register the application
    application_plattform.register()

    # create the device resource with the token (may be the push token or the registration id)
    sns_device = SNSDevice(application_plattform, token)

    # register the device with sns or update the token/the attributes
    sns_device.register_or_update(new_token=token, custom_user_data="customer_name={0}".format(Device.dealer.full_name)) 

    # this is importat: after updating or registration, your sns resource should have a arn. save this to your database.
    if sns_device.arn:
        device.arn = sns_device.arn
        device.save()           

Can you help here? do you have any idea what could be the problem?
Thanks

[melbic]

Just to check. Did you import APNApplication?

from scarface.models import SNSDevice, APNApplication

[Dealers]

No I didn't since it is not in the documentation... I will add it. It will be great if you can add it to the doc as part of the setting.

Thanks a lot!

[melbic]

Already added it. Thank you for your input.

[Dealers]

Additional help is needed...
While this command is executed: application_plattform.register(),
I am getting this error:
Exception Type: BotoServerError
Exception Value:
BotoServerError: 400 Bad Request
{"Error":{"Code":"InvalidParameter","Message":"Invalid parameter: PlatformPrincipal not valid.","Type":"Sender"},"RequestId":"d027b359-0dd4-5296-9dd9-fe748596113c"}
Exception Location: C:\Python27\lib\site-packages\boto\sns\connection.py in _make_request, line 765

Any idea?
Thanks