MATLAB: Invalid object handle error

handleMATLABobject

I have the following code which is a graphic rendering of the movement of a satellite around the Earth.
function ex
global state;
fh = figure('Menu','none','Toolbar','none','Units','characters');
hPanAni = uipanel('parent',fh,'Units','characters','Position',...
    [22.6 10.4 53 23],'title','Controls','FontSize',11,...
    'FontAngle','italic','FontWeight','bold');
hIniAni = uicontrol(hPanAni,'Style','pushbutton','Units','normalized',...
    'Position',[0.14 0.75 0.5 0.12],'String','Spin',...
    'FontSize',10,'Callback',@hIniAniCallback);
hFinAni = uicontrol(hPanAni,'Style','pushbutton','Units','normalized',...
    'Position',[0.14 0.5 0.5 0.12],'String','Stop',...
    'FontSize',10,'Callback',@hFinAniCallback);
hResetAni = uicontrol(hPanAni,'Style','pushbutton','Units','normalized',...
    'Position',[0.14 0.25 0.5 0.12],'String','Reset',...
    'FontSize',10,'Callback',@hResetAniCallback);
hPantSim = uipanel('Parent',fh,'Units','characters',...
    'Position',[107.87 8 157.447 42],'BorderType','none','title',...
    'Screen','FontSize',11,'FontAngle','italic',...
    'FontWeight','bold');
hPantSimInt = uipanel('Parent',hPantSim,'Units','normalized','Position',...
    [0 0 1 1],'BorderType','line','BackgroundColor','black');
ah4 = axes('Parent',hPantSimInt,'Units','normalized','Position',...
    [0 0 1 1],'Color','none','Visible','off','DataAspectRatio',...
    [1 1 1],'NextPlot','add');
rotate3d(ah4);
hgrot = hgtransform('Parent',ah4);
T1 = 0:pi/100:2*pi;
Y = zeros(numel(T1),3);
Y(:,1) = 7000*cos(T1);
Y(:,2) = 7000*sin(T1);
xmin = min(Y(:,1));
ymin = min(Y(:,2));
zmin  = min(Y(:,3));
xmax  = max(Y(:,1));
ymax  = max(Y(:,2));
zmax  = max(Y(:,3));
Resf = 6378;
xmin2 = min(xmin,-Resf);
xmax2  = max(xmax,Resf);
ymin2 = min(ymin,-Resf);
ymax2  = max(ymax,Resf);
zmin2  = min(zmin,-Resf);
zmax2  = max(zmax,Resf);
set(ah4,'XLim',[xmin2 xmax2],'YLim',[ymin2 ymax2],'ZLim',[zmin2 zmax2]);
maptext = imread('tierra.jpg');
[X_im, map] = rgb2ind(maptext,128);
[x_esf,y_esf,z_esf] = sphere(50);
x_esf = Resf*x_esf;
y_esf = Resf*y_esf;
z_esf = Resf*z_esf;
props.FaceColor= 'texture';
props.EdgeColor = 'none';
props.Parent = hgrot;
props.Cdata = flipud(X_im); % it is necesary to do this for getting the 
% appropiate image on the sphere
surface(x_esf,y_esf,z_esf,props);
colormap(map);
axis equal vis3d;
view(3);
az = 0;
Fin = numel(T1);
k = 2;
ind_ini = 0;
state = 0;
handles.tray = zeros(1,Fin);
handles.psat = line('parent',ah4,'XData',Y(1,1), 'YData',Y(1,2),...
    'ZData',Y(1,3),'Marker','o', 'MarkerSize',10,'MarkerFaceColor','b');
       function hIniAniCallback(hObject,evt)
            if (ind_ini == 1)
              return;  
            end
            ind_ini = 1;
            state = 0;
            while (k<Fin)
            az = az + 0.01745329252;
            set(hgrot,'Matrix',makehgtform('zrotate',az));
            handles.tray(k) = line([Y(k-1,1) Y(k,1)],[Y(k-1,2) Y(k,2)],...
                [Y(k-1,3) Y(k,3)],...
        'Color','red','LineWidth',3);
            set(handles.psat,'XData',Y(k,1),'YData',Y(k,2),'ZData',Y(k,3));
            pause(0.02); 
            k = k + 1,
              if (state == 1)
                  state = 0;
                  break;
              end
              end 
         end
      function hFinAniCallback(hObject,evt)
          ind_ini = 0;
          state = 1;
      end
   function hResetAniCallback(hObject,evt)
      set([handles.tray,handles.psat],'Visible','off');
      k = 2;
      ind_ini = 0;
      state = 1;
      az = 0;
      set(hgrot,'Matrix',makehgtform('zrotate',az));
      handles.psat = line('parent',ah4,'XData',Y(1,1), 'YData',Y(1,2),...
      'ZData',Y(1,3),'Marker','o', 'MarkerSize',10,'MarkerFaceColor','b');
  end
end
However, when I copy it to my main program I get the following error message:
??? Error using ==> surface Invalid object handle
    Error in ==> simorbiv8v3>hIniPropCallback at 1911 surface(x_esf,y_esf,z_esf,props);
    ??? Error while evaluating uicontrol Callback
I do not understand what is happening.

Best Answer

Command
dbstop if error
and then run the code. When it stops at that line, examine props.Parent and in particular check ishandle(props.Parent) . If it says that it is not a handle, chase further up to ah4 and make sure that it is still a handle, then up to hPantSimInt and then to hPantSim and then to fh
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