MATLAB: Type of error – Subscripted assignment dimension mismatch

In my main function,outside my for loop in which the calculations are done, I created an array:

driTable = zeros(length(A),2);

where length(A) = 5

I have a function with 2 outputs which have been formatted to 1dp within the function, and has been called in the main function:

[driInput1, driInput2] = dri_calculate( z,z2,beta,g);

This how the outputs have been calculated

driInput1 = sprintf('%4.1f',driInput);
driInput2 = sprintf('%4.1f',driInput);

driInput is calculated from:

driInput = ((beta^2)/g)*(max(z));

Once I've returned these outputs to the main function, I do this:

 driTable(k,1) = driInput1;
 driTable(k,2) = driInput2;

where "k" is the counter of a for-loop. At:

 driTable(k,1) = driInput1;

is where I get my error message. The thing is before I did sprintf and just outputted driInput, I didn't get an error message.