Cygwin - diff command does not provide output

Dear Sir,
I am using Cygwin for the purpose of comparing files.
I tried to compare the files in two different directories and directed the output into another directory.
I could achieve this by writing a serious commands. But when I did that I gave the file name for the diff output as difffile1,difffile2 etc.,
 
But after some time "diff" command does not work correctly.
If I type diff x.txt y.txt
I simply get the result as "Files x y differ". But I am not getting the output of what exactly differ as I was getting before.
I think I have changed something.But I do not know what exactly I have changed.
The version of diff : (GNU diffutils) 2.8.7
 
Can you please help me overcoming this problem?
 
Thanks in advance
astro