The problems are twofold.
The easy one is that you used the literal index instead of the vector index for the stiffness matrices Ke[1, etc.
The real problem was that an expression is interpreted differently by the numeric and the symbolic processor and therefor the sheet would still not run. Obviously the pdf shows a Mathcad 11 (or below) file where a dfífferent symbolic engine was implemented in Mathcad (Maple).
The expression creates a 2-dimensional matrix using three range variables, which is quite unsusual, to say the least. Nevertheless either an error message should pop up, telling us that this is not allowed or both, the numeric and the symbolic engine, should create the very same matrix, which they don't do.
So I call this a bug!
The numerics create the correct 3x4 matrix while the symbolics just creates a 3x3 matrix.
I am not sure know how an expression with three ranges is supposed to work (best guess is like three nested for-loops) but it looks like the symbolics is missing the case j=2 and k=0.
I created an expression which uses just two ranges and does (hopefully) the same.
Anybody an explanation for this effect and/or a less cumbersome solution?
EDIT: Here is an alternative for the creation of the matrix "top" using a program with three nested loops. Its more obvious here that it does the same as the original expression:
[Sorry! Can't embed the screenshot. Whenever I try I end up with the same picture as above showing and not the one I selected to embed :-(]
Now on the last try it worked :-)