Android :: Code For Pulling Images From Web

I'm using the following code to grab images from the web. It uses Gridview and depending on position, picks a URL from an array. It works but the loading of images is often hit or miss. Almost every time I start the app, a different number of images load. It also has issues when changing from portrait to landscape view, 5 out of 10 images may be displayed then I'll turn the device and usually lose all the images. Sometimes a few do show up though. Any ideas on making this more robust?

try { URLConnection conn = aURL.openConnection();
conn.connect();
InputStream is = conn.getInputStream();
BufferedInputStream bis = new BufferedInputStream(is);
Bitmap bm = BitmapFactory.decodeStream(bis);
bis.close();
return bm;
} catch (IOException e) { Log.d("DEBUGTAG", "error...");
} return null;