Opening PDF documents on and iPad the scrolling doesn’t work

I have a SkyDive Account that I use with my students.  I have given them the link to a folder and then they can browse the folder to go to the place they want to.  If they open a document on the iPad, then it will open and show the first page.  However, if you try to scroll down it doesn't work.  This is all happening in Safari.  IF I go to a new tab in Safari, and then go back to my document, it will work.  I'm trying to figure out why this doesn't work the first time.  My students get very frustrated in seeing that the document is 4 pages long and they can only see the first page.  Any ideas?  The docuement scrolls perfectly on a  PC or MAC.