Realtime shadows against a lightmapped surface on mobile devices

I’m attempting to display some realtime shadows on mobile devices (iPad 4, some Android phones). The shadows are displayed against a lightmapped surface, and this works fine running on my laptop. However, displaying the same scene on mobile devices does not show the shadows. If I remove the lightmap, the shadows show up properly on the mobile devices.

It sounds like the capability to display realtime shadows on mobile devices was only recently added in Unity 4. Is this a limitation in the implementation?

Check you Quality settings, most likely your default iOS and Android quality setting has shadows disabled.