Tale the 'cm' out of there.
You get a choice between cm and inches so you can't enter units as M or mm etc.
[edit] fwiw, you can change between inches & cm via the button shown here:
[image: oLnJ_dc_units.jpg]
as far as the # error, i'm not 100% sure what it means but i think it's something like "DC is expecting a number but you entered a text string"