The problem is that your code only uses the filename, but you need to also provide the filepath (otherwise how does MATLAB know where the file is saved?). The filepath is provided as the second output of uigetfile:
[F,P] = uigetfile();
Results1 = fullfile(P,F);
Important: you should fclose every file that you fopen, otherwise your code will just collect more and more handles to open files, which can eventually cause various problems (errors, unresponsive, etc.)
Tip: you should name your variable with something more descriptive, i.e. that actually reflects their content and type.