ABAQUS: Thermal loading application problem

Hello, 

I am having some difficulties implementing a 2D thermal analysis in ABAQUS (my experience using this software is close to zero). In particular my query consist on the application of the convection heat transfer coefficient into edges and faces.

I have created a simple example to show you how I am currently doing this (see attached). Basically I simply add a temperature boundary condition on one edge and the convection is modelled as “interactions” in ABAQUS. However it seems like the interactions are applied to edges only and not the surfaces themselves (I am referring to surface "SN" in the attached file). There are two faces in the model connected using a “tie” type constraint but I am not sure if this is necessary. 

The results obtained following this method doesn't make sense to me.

Would it be possible for you have a quick look at the procedure and let me know your thoughts?

Thank you!