XValidation problems

Hello,

my problem is that I want use the XValidation operator to train a model of cluster centroids with external data.

I've got a some cluster centroids as an input and want to train them with XValidation using a dicision tree and a modelapplier with classification performance. Between this operator I tried to put an input operator (Example Source) and want to use it in the test path of XValidation.
How can I do this?

Thanks
Xeixes