BPSK BER simulation

correlative detector for BPSK signal

I need to solve the problem with BER calculation. I made a coherent correlation
type detector in MATLAB for a BPSK signal, but when I demodulate the noised
signal BER is much worse than it sould be in theory for coherent detection. I
add noise using awgn() function setting the desired SNR[dB]. I assume
Eb/No[dB]=SNR[dB]+10log(Tbit/Tsample) So why is it? My M-files are attached. I
used 1000 bits to simulate and SNR=-12dB which equals according to the equation
Eb/No=8dB. Theoretically the result shoul have been around 1e-4 and I get
BER=4e-2. The BER curves of the desired and of the reality I have are also enclosed.
Please help!