Error when trying to obtain transfer function from state space representation in MATLAB

A = [-4 0 5 2;0 0 0 0;0 0 0 1;-6 0 -1 -2];

B = [1 2;0 0;0 0;0 5];

C = [1 0 0 0;0 1 0 0;0 0 1 0; 0 0 0 1];

D = zeros(4,2);

[nom, denom] = ss2tf(A,B,C,D,1

sys_tf = tf(nom,denom)

Error:

Error using tf (line 287)

The values of the num and den properties must be row vectors or cell array of row vectors, where each vector is nonempty and containing numeric data.