Firstly, you are redefining Mathcad units as variables (N, A, ton, W). That's why the variable names have little squiggly lines under them in the definitions: it's a warning. Don't do that and expect units to then work correctly. Use different variable names. It's not the source of the problem, but if you do that then one day it will be.
It looks like the equation for Ke is an empirical equation. That means the values of Po and Bm should be unitless, but should be correct numerical values for the units expected for the empirical equation. So you should divide Bm and Po in the expression by the units expected for the empirical equation (which may not be the same as the units you used to define the variables!)
