How to solve bit error rate problem?

rx_bs = waveform2bitseq(rx_wave,SPB); % change waveform to bit sequence
rx_msg = bitseq2text(rx_bs); % change bit sequence to text message

tx_bs=rand(1,1280)>0.5; % generate sequence of 1280 random bits

SPBlist = 1:15;             % list of bit times to test
num_SPB = length(SPBlist);  % number of bit times to test
BER = zeros(1,num_SPB);     % initialize bit error rate array

for i = 1:num_SPB         %generate the SPB list
    SPB = SPBlist(i);
    tx_wave = format_bitseq(tx_bs,SPB);  % create waveform following protocol
    rx_bs = waveform2bitseq(rx_wave,SPB,0);  % decode received waveform
    BER(i) = compute_BER(rx_bs,rx_msg);  % compute the BER
end

This is my code and when I run this there is an error on

BER(i) = compute_BER(rx_bs,rx_msg); % compute the BER

How can I solve this?

[Jan]

If you mention, that there is an error, it is useful if you post the error message. It is much easier to solve a problem than to guess, what the problem is.