Plot doesn't show anything

I'm trying to plot the orbit diagram of the logistic map, but the plot doesn't show anything. There are no error messages, so I'm stuck...

close;
clear;
orbit=zeros(1,300);
j=0;
% parameter range
for(r=2.8:0.001:4)
    j=j+1;
    % random nitiation of iteration
    xn1=rand(1);
        for(i=1:600)
        % calculate logistic map
        xn=xn1;
        xn1=r*xn*(1-xn);
       % wait for transients
       if(i>300)
           % store the orbit points
           orbit(i-300)=xn1;
       end
    end
    plot(r,orbit);
    if(j==1)
        axis([2.8 4 0 1]);
    hold;
    end
    end

Answer 1

[Star Strider]

Try this slight edit of your code:

orbit=zeros(1,300);
j=0;
% parameter range
rv=2.8:0.001:4;
for k = 1:numel(rv)
    r = rv(k);
    j=j+1;
    % random nitiation of iteration
    xn1=rand(1);
    for i=1:600
        % calculate logistic map
        xn=xn1;
        xn1=r*xn*(1-xn);
        % wait for transients
        if(i>300)
            % store the orbit points
            orbit(i-300,k)=xn1;
        end
    end
%     plot(r,orbit,'.');
    if(j==1)
        axis([2.8 4 0 1]);
        hold;
    end
end

figure
plot(rv, orbit, '.');
axis([2.8 4 0 1]);