The example string given to explain Caesar encryption on the worksheet cannot be decrypted using the simple frequency analysis suggested on the worksheet. The text is too short and `E' does not occur with highest frequency.

I have put a longer example string (again all spaces and punctuation marks deleted, only upper case letters from `A' to `Z') in

www.cs.bham.ac.uk/internal/courses/java/msc/resources/exercise-sheets/s5_4.txt

You may want to use this string to test your program.