QPSK - Raised Cosine Filter - Error Rate Calculation

I'm trying to build a Simulink Model os a QPSK with Raised Cosine Filter system. I'm using, in the following order: Bernoully Binary Generator ( 1e-7 Sample time, double output data type) - QPSK Modulator Baseband (Input Tipe Bit, Gray Code) - Raised Cosine Transmit Filter (Group Delay 5, Rollof Factor 0.5, Upsampling Factor 4) - Complex to Real/Imag - the real part multiplied by sinus, Imag part multiplied by cos - Sum block - AWGN Channel (2 bits per symbol, 1/(2*8) power) - the output multiplied by sinus, and by cos making two different ways - Raised Cosine Receive Filter ( input samples per symbol (N) =4, group delay=5) - Complex to Real/Imag - Sign (as threeshold) - Real/Imag to Complex - QPSK Demod Baseband (Output type bit) - Error Rate Calculation (Receive Delay =24, Computation delay = 0, computation mode =entire frame, Output data=port).

I think everything is fine, but when I try the simulation, it only makes one result (I set the simultaion to stop at a concret number of errors, but it makes just one simulation), and the result of the BER is really bad (like 0.485). Do you know why that's happening?

Thank you!

[Cheng]

Use the function "finddelay(x,y)" to determine the estiamted system delay to check if your "receive delay" is set correctly.

Hope it helps.