I'm the site Administrator. I had someone else try on an AT&T phone with older android operating system and he get the same error message. Download unsuccesful. If the PDF is on public site it works fine. In secure area the PDF won't donwnload. JPG files download without problems. As indicated these don't exist on iphone. Works like a champ. I believe it's an android problem since it happens on multiple android OS and different carriers AT&T & Verizon on different phones.