I've got a class (ArrayMenu) which uses class (Keyboard) to read which key is pressed to choose from a menu. Keyboard compiles but ArrayMenu has this error (and I don't understand what I've done wrong!) Any one help - please!

---------- javac ----------
ArrayMenu.java:33: cannot resolve symbol
symbol : variable Keyboard
location: class ArrayMenu
choice = Keyboard.readChar();
^
1 error
Output completed (1 sec consumed) - Normal Termination

If anyone wants to see the code for the classes I will post them