Custom Plot Function of Subplots in Optimizaion

Hi, in my customized plot function, each time one function is called for the current x, outputting a 1*3 vector f3. I want to show the history of all the 3 values in f3. Below is the code. It's not working properly, as directly after the very first iteration, the 3-by-1 subplots were refreshed to a 1-by-1 axes, and further reset data operations cannot catch the settings. Thanks a lot for the help!

function stop = optimplotx_my(x,optimValues,state,varargin)

stop = false;

switch state
    case 'iter'        
        % Reshape if x is a matrix
        x = x(:);
        xLength = length(x);
        f3 = func(x);       % f3 : 1 by 3
        iteration = optimValues.iteration; 

          if optimValues.iteration == 0
              subplot(3,1,1);          
              sub1 = plot(iteration,f3(1),'kd');
              set(sub1, 'Tag', 'axes1')

              subplot(3,1,2, 'Tag', 'axes2');         
              sub2 = plot(iteration,f3(2));
              set(sub2, 'Tag', 'axes2')

              subplot(3,1,3, 'Tag', 'axes3');
              sub3 = plot(iteration,f3(3),'bd');
               set(sub3, 'Tag', 'axes3')

          else

              subplot(3,1,1)
              sub1 = findobj(get(gca,'Children'), 'Tag','axes1'); 
              newX = [get(sub1,'Xdata') iteration];
              newY1 = [get(sub1,'Ydata') f3(1)];            
              set(sub1,'Xdata',newX, 'Ydata',newY1);

              subplot(3,1,2)
              sub2 = findobj(get(gca,'Children'),  'Tag','axes2');
              newX = [get(sub2,'Xdata') iteration];
              newY2 = [get(sub2,'Ydata') rgb(2)];
              set(sub2,'Xdata',newX, 'Ydata',newY2);

              subplot(3,1,3)
              sub3 = findobj(get(gca,'Children'),  'Tag','axes3');    
              newX = [get(sub3,'Xdata') iteration];
              newY3 = [get(sub3,'Ydata') f3(3)];
              set(sub3,'Xdata',newX, 'Ydata',newY3);
          end

end