Thermal conductivity units error
I am new to Mathcad and in the process of learning. When defining the units of thermal conductivity k=W/m.K, I keep getting an error for the m.K part. Mathcad says it is an undefined variable even though m (for length) and K(for temperature) are both part of units recognized by Mathcad. I am using prime 6.0 version. Appreciate any help I could get.

