How to display surface with transparent enabled texture mapping?

Greetings community,

I have a question regarding a GUI that I am building...

I need to display two images, really two sprites; I managed to write some code in order to display a surface with a texturemap over it, and this appears like a sprite in a 2D graphical scenerio, but the transparent layer appears as a solid color...

How can I diplay the graphic map (X2) as a typical 2D game sprite (the code needs to run over Matlab 2011) with non drawing parts/colors?

This is the code I wrote:

function Image_Rotating()
X1 = imread('Sprite_fixed.png');
X2 = imread('Sprite_mobile.png');%This contains transparent layer, also                %set a color as transparent can be useful, as it is done in 2D games

C1 = X1;
C2 = X2;

MainFigureHdl = [];
MainAxesHdl = [];
SpriteHdl = [];
FixedSpriteHdl = [];

Sprite.XGRID = [];
Sprite.YGRID = [];
sprite_size =  [255 240];

[Sprite.XGRID, Sprite.YGRID] = meshgrid([-ceil(sprite_size(2)/2):floor(sprite_size(2)/2)], ...
            [ceil(sprite_size(1)/2):-1:-floor(sprite_size(1)/2)]);

fig = figure;  

MainAxesHdl = axes('Parent',fig,'XLim',[-300 300],'YLim',[-300 300],'ZLim',[-300 300]);   

FixedSpriteHdl=surface(Sprite.XGRID,Sprite.YGRID,zeros(size(Sprite.XGRID)),C1,...
    'FaceColor','texturemap',...
    'EdgeColor','none',...
    'Visible','on',...
    'CDataMapping','direct',...
    'Parent', MainAxesHdl);

SpriteHdl=surface(Sprite.XGRID,Sprite.YGRID,zeros(size(Sprite.XGRID)),C2,...
    'FaceColor','texturemap',...
    'FaceAlpha',1,...
    'AlphaDataMapping','direct',...
    'EdgeColor','none',...
    'Visible','on',...
    'CDataMapping','direct',...
    'Parent', MainAxesHdl);

Angle = 0;
view(2)    

while(Angle<361)
    Sprite_Rotate(deg2rad(Angle),Sprite.XGRID,Sprite.YGRID,SpriteHdl,C2);
    Angle = Angle + 1;
    drawnow;%Later, drawnow will be time-managed in order to obtain desired fps
end

end

function Sprite_Rotate(Angle,XGRID,YGRID,Sprite_ID,Sprite_GFX)
        % move bird to pos [X Y],
        % and rotate the srite surface by X degrees, anticlockwise = +
        cosa = cos(Angle);
        sina = sin(Angle);
        xrotgrid = cosa .* XGRID + sina .* YGRID;
        yrotgrid = sina .* XGRID - cosa .* YGRID;
        xtransgrid = xrotgrid;
        ytransgrid = yrotgrid;
        set(Sprite_ID, 'XData', xtransgrid, ...
            'YData', ytransgrid, ...
            'CData',Sprite_GFX);
end