Matlab draw 'subaxis' based subplots on specified 'axes'

Hi smart guys,

I am coding some GUI staff using Matlab. And I want to plot a figure with subfigures in one specified 'axes' using 'subaxis' method (which can be download on Matlab FX [subaxis.m][1]).

The program behaves quite right at first. As the subfigures are updating by one click button. Then the error pops-up. I simplify the problem and write some testing codes as following:

    % Specify an 'axes' in my GUI (here is an example of axes handle called 'ax')
    ax = axes;
    axes(ax); 
    cla(ax, 'reset');

    % Plot something using 'subaxis' with multiple subfigures 
    x = 0:0.1:10;
    spacing = 0.0;
    subaxis(3,1,1,'Spacing',spacing);
    plot(x,rand(size(x)),'k')
    legend('D','Location','NorthWest')
    ylim([-0.2 1])
    set(gca, 'box','off')
    set(gca,'XAxisLocation','top')

    subaxis(2,'Spacing',spacing);
    plot(x,rand(size(x)),'r')
    legend('C','Location','NorthWest')
    ylim([-0.2 1])
    set(gca,'xtick',[],'box','off','xcolor','w')

    subaxis(3,'Spacing',spacing);
    plot(x,rand(size(x)),'b')
    legend('B','Location','NorthWest')
    set(gca, 'box','off')

The program is fine at this point and did what I expected. Now I press a button to update these subfigures, but still want to plot the subfigures in the specified axes called 'ax':

    axes(ax); 
    cla(ax, 'reset');

    x = 0:0.1:10;
    spacing = 0.0;
    subaxis(3,1,1,'Spacing',spacing);
    plot(x,rand(size(x)),'k')
    legend('D','Location','NorthWest')
    ylim([-0.2 1])
    set(gca, 'box','off')
    set(gca,'XAxisLocation','top')

    subaxis(2,'Spacing',spacing);
    plot(x,rand(size(x)),'r')
    legend('C','Location','NorthWest')
    ylim([-0.2 1])
    set(gca,'xtick',[],'box','off','xcolor','w')

    subaxis(3,'Spacing',spacing);
    plot(x,rand(size(x)),'b')
    legend('B','Location','NorthWest')
    set(gca, 'box','off')

Error shows up!!!

    Error using axes
    Invalid object handle

Not sure what to do as the error info is so brief. It seems the subaxis can only be plot to a specific 'axes' once.

Any help would be appreciated. Thanks very much. A.

[1]: http://www.mathworks.co.uk/matlabcentral/fileexchange/3696-subaxis-subplot