Exception in Presentation.Write()

Hi!
On some presentations I get an error writing the new presentation to a stream:
Stack trace:

at xed09de6bc728e32e.x8d0fad9d5daf8d6b.GetSize(Int32 codepage)
at xed09de6bc728e32e.x10d7a1cae426b158.GetSize()
at xed09de6bc728e32e.x5704d66afcf29611.GetSize()
at xed09de6bc728e32e.x5704d66afcf29611.Write()
at Aspose.PowerPoint.Presentation.Write(Stream stream)
at MessageProcessorPPT.MakePPT.SaveNewPresentationToDB() in c:\\development\\ifab-intranet\\ifabservice\\ifabmsmq\\messageprocessorppt\\makeppt.cs:line 516

Any idea?

I found it!

Presentation.Title was NULL and so I get an exception!

Surprise, surprise!