[Qgis-developer] timtut2: error message loading data

[Sven Bauhan]

Hi,

I am new here and dont know if this is the correct place for this question.

I want to write an Editor for geographical data based on the QGis libraries. 
So i tried to compile and understand the code examples from Tim Sutton.

The examples compile but in example 2 the loading of data fails with the 
messages:

Failed to load
Layer is NOT valid

But the data seem to be correct, as it can be loaded into the QGis 
Apllication.
Are there some hints to find out what the problem is?

Thanks,
Sven Bauhan