Question: Multiplying Matrices

I'm not sure what I am doing wrong. I was given 2 matrices to find B^T*(M^-1)*B where M is a 10x10 matrix and B is a 10x5 Matrix. 

Matrix(10, 10, [[1, 0, 0, 0, 1/2, 0, 0, 0, 0, 0], [0, 1/2, 0, 0, 0, 0, 0, 1/3, 0, 0], [0, 0, 1/2, 0, 0, 0, 0, 0, 1/3, 0], [0, 0, 0, 1/3, 0, 0, 0, 0, 0, 0], [1/2, 0, 0, 0, 1/3, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 1/3, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 1/4, 0, 0, 0], [0, 1/3, 0, 0, 0, 0, 0, 1/4, 0, 0], [0, 0, 1/3, 0, 0, 0, 0, 0, 1/4, 0], [0, 0, 0, 0, 0, 0, 0, 0, 0, 1/4]]);

M := rtable(1 .. 10, 1 .. 10, [[1, 0, 0, 0, 1/2, 0, 0, 0, 0, 0], [0, 1/2, 0, 0, 0, 0, 0, 1/3, 0, 0], [0, 0, 1/2, 0, 0, 0, 0, 0, 1/3, 0], [0, 0, 0, 1/3, 0, 0, 0, 0, 0, 0], [1/2, 0, 0, 0, 1/3, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 1/3, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 1/4, 0, 0, 0], [0, 1/3, 0, 0, 0, 0, 0, 1/4, 0, 0], [0, 0, 1/3, 0, 0, 0, 0, 0, 1/4, 0], [0, 0, 0, 0, 0, 0, 0, 0, 0, 1/4]], subtype = Matrix); 'M';
                               M
Matrix(10, 5, [[0, 0, 1/3, 0, 0], [0, 0, 0, 0, 0], [0, 0, 0, 0, 0], [0, 1/4, 0, 0, 0], [0, 0, 1/4, 0, 0], [0, 0, 0, 1/4, 0], [1/2, 1/2, 1, 0, 0], [1, 1/2, 1/2, 1, 0], [0, 1, 1/2, 1/2, 1], [0, 0, 1, 1/2, 1/2]]);

B := rtable(1 .. 10, 1 .. 5, [[0, 0, 1/3, 0, 0], [0, 0, 0, 0, 0], [0, 0, 0, 0, 0], [0, 1/4, 0, 0, 0], [0, 0, 1/4, 0, 0], [0, 0, 0, 1/4, 0], [1/2, 1/2, 1, 0, 0], [1, 1/2, 1/2, 1, 0], [0, 1, 1/2, 1/2, 1], [0, 0, 1, 1/2, 1/2]], subtype = Matrix); 'B';
                               B
`~`[`*`](`~`[`*`](B^%T, 1/M), ` $`, B);
Error, dimension bounds must be the same for all container objects in an elementwise operation