Going through the comments it is evident that when calling
S(ID,ID,ID) = S(ID,ID,ID) + K;
The size of S(ID,ID,ID) is 4*4*4 and size of K is 6*6 which doesn't match and thus you will be getting a error as:
Array dimensions must match for binary array op.
You must change your code accordingly making sure that the dimensions match.