Problem in link face mesh for periodic
 

Hi

I created a face mesh, e.g. rectangular shape and copy the face by rotation to create a second face mesh in GAMBIT. I want both face mesh to be periodic boundaries. Therefore, I try to link the two face meshes by selecting the two face mesh and all vertices associated with the face mesh. However, I got an error "cannot link faces face.1, face.2 due to all loops of edges not being specified." Can anyone enlighten me on how to get rid of this error?

did you link surfaces before or after having meshed them?
can you add a picture?