[Kwant] semicon

Hello I want to find conductance of a heterostructure using semicon library. When I just use coords='z', everything is OK. But, when I want to change it to two dimensions like 'xz', I encounter an error. Would you please tell me how I can fix it? I hope it is not just a simple mistake which I am not aware. Your time and consideration are greatly appreciated in advance. Please find attached the code correspondent to what I mentioned above. Best regards, Ali