You
load net.mat
but that file does not happen to contain a variable named Data
filename = 'CurahHujan.xlsx';
sheet = 2;
xlRange = 'D25:P36';
You define information about some data in an xlsx file, but you never read from the file.
By the way: these days we recommend readtable() or readmatrix() or readcell() instead of xlsread()