Problem with restoring of lightmap via code on iOS/Android

We have a big issue with reseting the lightmap for a scene after loading it additiv. Normaly we are loading the scene an restore the lightmap by setting the correct values:

aLightmapsDataList[aLightmapSetting.lightmapIndex].lightmapNear = aLightmapSetting.lightmapNear;
aLightmapsDataList[aLightmapSetting.lightmapIndex].lightmapFar = aLightmapSetting.lightmapFar;

after that we are setting all the gameObjects as static and call:

StaticBatchingUtility.Combine(aRendererGameObjectsArray, rootGameObject);

Till lately this was working fine and about 100 drawcalls were batched. (I have to wait one frame though after loading the scene before calling the function).
But currently we have the problem that on iOS and Android-Devices the drawcalls are not batched anymore.
To test this i added a GUI-Button to the project to reset the lightmap manually, to check if it is a execution-order-problem, but the GUI-Button is not changing anything. either the meshes are not combined or the batching doesn’t work properly.

In the editor the GUI-Button is also not working, strange thing is though that an Editor-Button that is calling the exact same function is working.
I debugged the functionality and there is no difference between calling the function via GUI-Button or via Editor-Button. So why is the one working and the other not?

Every hint or tip would be appreciated.

Thanks in advance

Chris

Just to let you know, i opened a bug ticked regarding this issue, since i could reproduce it in a separat project: FogBugz