Why won't my Mac load my datafile when I KNOW the filepath is correct? Am I missing something?

I've asked my lab TA's and they've all just said that most people with macbooks have this problem and to just use the lab computers. I would still like to know if I can fix this.

My filepath looks like this:

SourceDirectory=[ '/usr/ianpeterson/Desktop/Giraffe/ ']; % example for more complicated file path FileName=['data2014']; % use your calibration file name FileExtension=['.txt'];

The folder names "Giraffe" and it is sitting on my desktop. I have tried using both "Users" and "usr" with the same results; I simply get the error message "No such file or directory"