Problem in display a figure

Hi everyone,

Now I want to display a map using the App designer.

I have two questions, one is why I can't use the gray color in the colormap? I tried to change the color but doesn't work!

The other is why my figure is beyond the axis?

Below is the code and results:

                A = [ans(:,1),ans(:,2),ans(:,3)];
                clear ans
                X_1 = A(:,1);
                Y_1 = A(:,2);
                Z_1 = A(:,3);
                scatter(app.DEMview,X_1,Y_1,200,Z_1,'s','filled') 
                c = gray;
                colormap(c)
                colorbar(app.DEMview)
                hold on    
                

Thank you very much!