Can't assign two BPMN 2.0 models to one value chain simbol

Hello everyone

I've value chain model with a value chain simbol within. Also, in another folder, I've two different BPMN 2.0 Process Models. Both models represents the same business process but with different detail levels.

I want to create two different navigation links between value chain simbol and each BPMN process diagrams.

I link the first one BPMN model (over value chain symbol I click new->assign->existing model-> "BPMN Process diagram (BPMN 2.0)" type->and select the model) and works.

But if I try to assign the second BPMN model, the type "BPMN Process diagram (BPMN 2.0)" doesn't appear in the list of model types to choose. I don't know why¿?

Please, how can I link (navigation link) my value chain simbol with those two BPMN modeles? 

 Thanks very much