I had the same problem. and adding this code fixes the error, but still the tk2dCamera responds to the Portrait orientation, how can I do to only support Landscape modes?
edit
I had to edit the MainPage.xaml and set the SupportedOrientations="Landscape" attribute. This seems to be independent of the player configuration in the project settings :/
Foreground="{StaticResource PhoneForegroundBrush}" Orientation="Landscape" SupportedOrientations="Landscape" BackKeyPress="PhoneApplicationPage_BackKeyPress" OrientationChanged="PhoneApplicationPage_OrientationChanged">