I have gone through your problem. I have solution for your problem.
You are facing this issue because it may be the case that your output variables name and the method name both are the same.
Have a look at below code snippet as an example.
[stft, t, f]= stft(x,wlen,nfft);
In above snippet the method output variable in the left hand side is the “stft” and in the right hand side the method name is the “stft” also.
It can also happen that in the matlab program the variable name you have created is already the inbuilt method name of the MATLAB.
You should also pay attention to the input and output matrix columns of your program they might not be the same
so please check this type of mistakes in your code.