Slide.Background is null - possible office version bug

I have a ppt-file which for some reason does not have a Background object.

My file consists of 3 slides. The 2nd slide is very simple with a white backgground. When generating the dynamic content, the Slide objects BackGround property is null!!! (how can you not have a background?)

The BackGround property read-only so I cannot set it.

Here is the strange thing.

1. When I open my file, and change the background-color to black, the Background is no longer null.

2. It is possibly a Office Xp/ Office 2007 issue. When I open the file in Office 2007 and clicks "Save" it works. When I click "Save as", it doesnt work!

Could you provide ppt file please.
That definitely can’t be a problem of PowerPoint XP because it can’t create slides without background.
May be something new invented in PP2007 so please send us this ppt file for tests.

This is a zipped version of the file. When I open it and clicks “save” it works

It looks like PP2007 can create slides without background object.
We will implement workaround for that in the nearest future.
Currently, if slide doean’t have background the quick solution is create
rectangle with size equal to slide size and put it to back of all other shapes.

Please provide code sample as I cannot find any size Property on Slide object.

You can get the slide size with Presentation.SlideSize property.