Loader problem

I am loading an image with loader, and while the image is still loading, i want to cancel loading of current image, and start loading next image.

this is the code i have put before i request loader.load() again:

try{
loader.close();
loader.unload();
}catch(er:Error){}

the problem is that when next image is loaded, half or some part of the image is not there (part of the image is like grey) like it hasnt properly loaded or something…

does anybody know why is this happening?