When try to save a photo with Phlickr_Photo::saveAs(), Original photo format work fine but other not.
This method use buildImgUrl() method so buildImgUrl() return a good Url for SIZE_ORIGINAL but bad url for SIZE_75PX, SIZE_100PX, SIZE_240PX, SIZE_500PX, perhaps SIZE_1024PX.
Uses getSizes() method to compare Url :
$photo = new Phlickr_Photo( ........ );
$sizes = $photo->getSizes();
echo $sizes['s']['source']; // display the 75px url
echo $photo->buildImgUrl(Phlickr_Photo::SIZE_75PX); // display an other url wich does not work.