How to plot using the mod function?

I'm trying to plot an energy graph, and I'm having trouble plotting both the mod function. I don't understand why I cannot plot each point when mod(t,etime) == 0 and mod(t,ptime) == 0. The mod(t,etime) == 0 function only plots at the end, and I would like it to plot continuously. Could someone please help me figure this out?

 function MDSim(T,sigma,m,dt,rc,L,k,ptime,etime)
    tempcontrol=input('Would you like Temperature Control? [Y/N] \n','s');
    while (tempcontrol ~= 'n' && tempcontrol ~= 'y') 
        tempcontrol=input('Would you like Temperature Control? [Y/N] \n', 's');
    end

    [xpos,ypos,vx,vy]=Initialize(sigma,L,k);

    h=cell(8);

    for i=1:64   
        h{i}=rectangle('Position',[xpos(i)-0.5*sigma ypos(i)-0.5*sigma sigma sigma],'Curvature',[1 1], 'FaceColor','b');
        axis equal
    end

    t=0;
    while T > t
        t=t+1;
        [xpos,ypos,vx,vy,U_tot,K_avg_tot,E_tot]=Step(xpos,ypos,vx,vy,dt,m,L,sigma,rc,k,tempcontrol);   
        if mod(t,ptime) == 0
            for j=1:64
                figure(1);
                set(h{j},'Position',[xpos(j)-0.5*sigma ypos(j)-0.5*sigma sigma sigma])
                axis equal
            end 
        hold on
        drawnow
        hold off
        end
        if mod(t,etime) == 0

            %disp(['Total Energy is: ', num2str(E_tot)])
            figure(2);
            plot(t,(U_tot),'rd', t,(K_avg_tot),'b+',t,(E_tot),'m*')

            title('Total Energy (E), Potential Energy (U),Kinetic Energy (K) vs. Time (s)');
            xlabel('Time (ds)');
            ylabel('Energy (J)');
            legend('E','U', 'K', 'Location', 'EastOutside');

            hold on
            drawnow()

            hold off
        end

    end
end
    %

Answer 1

[Walter Roberson]

You appear to be successfully plotting at the times you would like to. You just are not asking for the plot that you think you are.

        if mod(t,etime) == 0

            disp(['Total Energy is: ', num2str(E_tot)])
            disp(count);

            plot(t, (U_tot), '*')    %notice change
            axis equal
            %scatter(t,E_tot);
            %set(ph, 'XData', t);
            %set(ph,'YData', U_tot);
            %,t,K_avg_tot,'-',t,E_tot,'-')
            hold on                 %notice change
            drawnow()               %notice change

        end

[Akhil Vasvani]

Thank you, your answers works for one part, but it cannot work for both. How do I change my code to reflect this?

[Walter Roberson]

After

          h{i}=rectangle('Position',[xpos(i)-0.5*sigma ypos(i)-0.5*sigma sigma sigma],'Curvature',[1 1], 'FaceColor','b');

and

hold on

[Akhil Vasvani]

Thank you