why fft of modulated signal shows peak at carrier frequency?

    the fft of  fsk modulated signal should show only two peaks , one for "1" and other for "0" but my result shows one peak at carrier frequency. Why it is so?

clear 
clc

M=2;
fd=500;    %symbol frequency
fc=2000;      %carrier frequency

Fs = 8000;%sample frequency 8 KHz

t = [0:1/Fs:0.01];%time axis/vector for 10 msec

%Generating Sine Wave
s = sin(2*pi*1000*t);

% Quantization
predictor=[0 1];
partition=[-1:0.1:0.9];
codebook=[-1:0.1:1];
encodedx = dpcmenco(s,codebook,partition,predictor);

%decimal to binary conveersion
data_bin=de2bi(encodedx);

% FSK modulation
modulation=dmod(data_bin,fc,fd,Fs,'fsk',M);

% Demodulation
demod=ddemod(modulation,fc,fd,Fs,'fsk',M);

%binary to decimal conversion
data1=bi2de(demod);

% dequantization
decodedx = dpcmdeco(data1,codebook,predictor);

% BER calculation
[num,BER]=biterr(data_bin,demod)

% Taking FFT
%Message Signal
figure
S = fft(s);
S = abs(S(1:round(length(s)/2)+1));
frqS = [0:length(S)-1]*Fs/length(s);
subplot(3,2,2);
plot(frqS,S) 
title('Spectrum of Message Signal')
xlabel('Frequency (Hz)')
ylabel('Amplitude')

%Modulated Signal

S = fft(modulation);
S = abs(S(1:round(length(modulation)/2)+1));
frqS = [0:length(S)-1]*Fs/length(modulation);

subplot(3,2,4);

%plot(f,abs(Y(1:NFFT/2+1)))
plot(frqS,S) 
title('Spectrum of Modulating Signal')
xlabel('Frequency (Hz)')
ylabel('Amplitude')

%Demodulated Signal
S = fft(decodedx);
S = abs(S(1:round(length(decodedx)/2)+1));
frqS = [0:length(S)-1]*Fs/length(decodedx);
subplot(3,2,6);
plot(frqS,S) 
title('Spectrum of Demodulated Signal')
xlabel('Frequency (Hz)')
ylabel('Amplitude')

subplot(3,2,1); plot(t,s);title('message signal');
subplot(3,2,3); plot(modulation(1:400));title('Modulated signal');
subplot(3,2,5); plot(t,decodedx);title('DEModulated signal')