"The graphic format you selected requires the optional graphic export library..."

If you are using Prism 3, this message means what it says. With Prism 3, the graphics export library was a separate installation. Write to us for a new installer. Include your serial number. 

If you are using Prism 4 or later, the wording of message is quite misleading, since there is no optional graphics export library. Prism Windows shows this alert when the file pzmexpr2.dll (which is installed with Prism) is missing from the Prism folder (or is badly damaged). Reinstall Prism to solve the problem.