Have you read the documentation for the inputs to csvread? You've told it to skip 9 columns, and it's giving you a very clear error message that there aren't that many columns in the entire file.
My guess is you're either having 0- vs. 1- based indexing troubles, or you actually meant to read all 9 columns, but told it to skip all 9 columns.
Try either:
testprim = csvread('ejemplo_4.csv',1,8,[1,8,734,8]); % Read the 9th column only
or
testprim = csvread('ejemplo_4.csv',1,0,[1,0,734,8]); % Read all 9 columns
