@ecterrab 

I'm sorry for my late reply but for some reason I've noticed just now your last message. However, I'm posting my worksheet, hoping that you'll be so kind to give it a look.

ChKN.mw

@ecterrab Thanks a lot for your answer! By the way, is there a specific reason for the fact that the Tensor package is not able to do this computation? Or is there any possible workaround which doesn't involve using other packages such as Physics? I'm just curious about the potentialities of the Tensor package.