Actually, on Samsung registers you'll want to go back to P mode and press CASH to end an incomplete programming operation.
When you tried the Initial Clear, did INITIAL CLEAR print on the receipt printer? If not, try again and make sure you follow the procedure EXACTLY.
Steve
September 2009
It is telling you that you are still in the middle of programming in the P position, so you cannot change modes until you finish the programming. Go back to P mode and try pressing No Sale as this will end most programming operations