Why can't I open a PDF on my iPad 2

After reading other posts, I changed the restrictions setting from "limited adult content" to "allow all" and it worked! Although I don't want this access on my ipad (I am a teacher and students use this ipad) I will have to allow it so I can open pdfs.

No, that is the problem. a screen opens that is completely white with no "open in" option. I can open pdfs from email just not from the internet. which is odd because I used to be able to open them. I have ibooks, pages, evernote and now adobe reader but no option to "open in." this happens with all pdfs from the internet. oh and I can these pdfs on my iphone.

I have pages and ibooks. Do I also need Adobe Reader? After I click on the PDF I get a new screeen but no picture (only blank white) and no options to open in another program.

I downloaded Adobe Reader, but still can't open pdf. A new tab opens but displays a white screen