noob help with switch/case

Hi. this is my first post here. I am starting a project at university in which a user can type a letter in, and the resulting music note comes out. I have created this using if/else, but on changing to switch I am having a problem. Everything works fine except the default line (in bold) executes regardless of whether the user presses one of the correct keys or not.

Below is my code.
Thanks, Adam

/* IPA main.cpp 2009/10 tjm */

#include "aservelibs/aservelib.h"
#include <stdio.h>
#include <math.h>


int main ()
{

	char keys = 'l';
	printf("Type a note and press 'Return'\n");
	/*begin loop*/
	while(keys != 'x')
	{
		scanf("%c", &keys);
		switch (keys)
		{
		case 'a': case 'A':
			aserveOscillator(0, 220.0, 1.0, 0);
			break;
		case 'b': case 'B':
			aserveOscillator(0, 246.94, 1.0, 0);
			break;
		case 'c': case 'C':
			aserveOscillator(0, 261.62, 1.0, 0);
			break;
		case 'd': case 'D':
			aserveOscillator(0, 293.66, 1.0, 0);
			break;
		case 'e': case 'E':
			aserveOscillator(0, (629.62/2), 1.0, 0);
			break;
		case 'f': case 'F':
			aserveOscillator(0, 349.22, 1.0, 0);
			break;
		case 'g': case 'G':
			aserveOscillator(0, 391.99, 1.0, 0);
			break;
		default:
			printf("That's not a note silly!\n"); /*This is the problem*/
			break;
		}

		 
		 aserveSleep(500);
		 aserveOscillator(0, 0, 0, 0);
		
	}
	
	aserveOscillator(0, 0, 0.0, 0);
    return 0;
}