Obviously you can't use a vector as end value for a range variable!
What result do you expect - a 3x3 matrix where each column represents the result for one value in N.b?
Doesn't make much sense with vectors consisting all of the same value.
And if your vector N.b would consist of different elelemnts, your set of results would be vectors of different lenghts. How would you like Mathcad to present those results? Obviously it can't be a matrix anymore but rather a vector consisting of those vectors.