Problem with "Rayleighchan" in MATLAB! Somebody he

Hello everybody !
I want to simmulate a Rayleigh channel with BPSK signal with following code
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chan=rayleighchan(1/10000,100);
M=2;
tx=randint(nbit,1,M);
dpsksig=pskmod(tx,M);
fadedsig=filter(chan,dpsksig);
snr=0:1:20;
for n=1:length(snr)
rxsig=awgn(fadedsig,snr);
rx=pskdemod(rxsig,M);
[nerrors,ber]=biterr(tx(2:end),rx(2:end));
end
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But BER [1*21] I get is terrible
[0.472647264726473 0.477147714771477 0.465246524652465 0.465346534653465 0.470547054705471 0.463746374637464 0.462746274627463 0.458845884588459 0.461246124612461 0.461546154615462 0.460046004600460 0.457145714571457 0.454145414541454 0.453945394539454 0.453345334533453 0.456245624562456 0.452745274527453 0.452245224522452 0.454945494549455 0.454645464546455 0.454845484548455]
It is different with theorical BER.
Why there is that difference? Someone can help me?