Add relation type between node entity an CRM contact causes blank screen

Hello,

I'm trying to use Erpal to control laboratorial tasks.
So I have the Laboratories and individual entities which are CRM contacts and I have a node which is the laboratorial analisys kit used to collect the procedure from these individual contacts.
I need to do both: create a relation between an analysis kit entity and a Laboratory contact crm entity and after a relation between an analysis kit entity and the individual who did the exam procedure.
But after create this relations on "Add relation type" and put this field on the analysis kit entity, any time I try create a new analysis kit node I got a blank screen.
I can't create this relation using the CRM relations because it just let me choose other CRM contacts as targets.

Is there any solution?