what is the problem in this convolutional code

THE CODE:

% rate 1/2 convolutional encoder 
% define trellis 
trellis = poly2trellis(7,[111 111]); 
% define input and output 
x = randi([0 1]); 
y = convenc(x,trellis); 
% define generator polynomials 
g1 = [1 0 1 0 1 1 1 0]; 
g2 = [1 1 1 0 1 1 0 1]; 
% encode 
y1 = mod(conv(y,g1),2); 
y2 = mod(conv(y,g2),2); 
% interleave 
z = [y1;y2]; 
z = z(:)'; 
% modulate 
M = 4; 
k = log2(M); 
y_tx = bi2de(reshape(z,k,length(z)/k).','left-msb'); 
% plot constellation 
scatterplot(y_tx,1,0,'k*'); 
axis([-5 5 -5 5]); 
% add noise 
EbNo = 10; 
snr = 10; 
y_rx = awgn(y_tx,snr,'measured'); 
% demodulate 
z_rx = de2bi(y_rx,k,'left-msb'); 
% de-interleave 
y1_hat = z_rx(1:2:end); 
y2_hat = z_rx(2:2:end); 
% decode 
tblen = 15; 
y_hat = vitdec(y1_hat,trellis,tblen,'trunc','hard'); 
% plot BER 
ber = berawgn(EbNo,'psk',M,'nondiff'); 
semilogy(EbNo,ber,'k*'); 
hold on; 
ber = berawgn(EbNo,'psk',M,'nondiff'); 
semilogy(EbNo,ber,'ko'); 
legend('Theoretical BER','Empirical BER'); 
xlabel('Eb/No (dB)'); 
ylabel('Bit Error Rate');

THE ERROR:

Error using vitdec

Length of the input code vector must be a multiple of the number of bits in an

input symbol.

Error in test2 (line 67)

y_hat = vitdec(y1_hat,trellis,tblen,'trunc','hard');

WHAT DOES IT MEAN?

Answer 1

[Jan]

There is another problem before:

% rate 1/2 convolutional encoder 
% define trellis 
trellis = poly2trellis(7,[111 111]); 
% define input and output 
x = randi([0 1]); 
y = convenc(x,trellis); 
% define generator polynomials 
g1 = [1 0 1 0 1 1 1 0]; 
g2 = [1 1 1 0 1 1 0 1]; 
% encode 
y1 = mod(conv(y,g1),2); 
y2 = mod(conv(y,g2),2); 
% interleave 
z = [y1;y2]; 
z = z(:)'; 
% modulate 
M = 4; 
k = log2(M); 
y_tx = bi2de(reshape(z,k,length(z)/k).','left-msb'); 
% plot constellation 
scatterplot(y_tx,1,0,'k*'); 
axis([-5 5 -5 5]); 

% add noise 
EbNo = 10; 
snr = 10; 
y_rx = awgn(y_tx,snr,'measured'); 
% demodulate 
z_rx = de2bi(y_rx,k,'left-msb'); 

Error using de2bi
Input must contain only finite real nonnegative integers.