I love it "when trades collide."

I also can guess where the confusion originated....MC and romex count the wires differently.

Of course, when you were given your instructions, you were not given any info as to the needs of the shade- you were expected to just "know" somehow!

If you're very lucky, the first romex was "fished" into place, and pulling a new one won't invlve tearing up the wall.