calculate the concentration of oxygen through porous support

Hi,

It is the first time I used Comsol, my project consist in the measure of gas permeability through porous support. Within Comsol I have already create the plan geometry and put the boundary and area parameters. Basically the project consist injecting nitrogen flow in one side and air flow in the other side, between both of them the porous support is insert, the aim is to calculate the concentration of oxygen passing through the porous membrane. I have just compute, it gives an error.
If anybody know how to fixed it I will be grateful, please find attached my file.

Thanks in advance,

Maxime