I bought a few manuals to use with my iPad online.  When I go to the iPad I, I cannot access those manuals and when I click on the marketplace it states that I have an online license and can't buy them.  Does that mean that you have two separate environments (web and mobile) and if you buy from one, you can't use it in the other?  Or should you buy from mobile and then its automatically available on Web? 

Its a bug in the mobile app.  You have to log off the mobile app, then log back on and the books are now available.  Not sure if its possible to change the warning message, but if you did it should cut down on your tech support issues.

If you buy a book on one place, you have the book on both the website and the app.

Try to close and ioen the app, forcing ut it sync.