Segregated groups error

Hi

I'm trying to simulate a microchannel of a methane steam reformer in COMSOL 4.3. The microchannel has 2 domains, a catalytic bed and a free flow. At first, I tried using 2 physics (Transport of Concetrated Species) for each domain to mass transfer, but I can't do a boundary condition between the domains. When I tried to compute, I had the error:

"Constraint found for variables in different Segregated groups. Try to merge these groups."

So, I tried to put both domains in the same physic, refiner mesh, change the variables of segregated groups and the same error persist. Does anyone know what can be done?

Thanks