Try asking your question at the manufacturer's on-line technical support site. I get a useful response about 50 percent of the time that way.
Owner's manuals often don't specify a maximum card size. Some manufacturer's will tell you what size and speed of cards a certain device was verified to work with during their factory testing. Often manufacturers don't re-test an older device when newer technology is introduced.
An 8Gb or 16 Gb Class 10 card is maybe $10 to $25? Try one and see if it works, if not you can likely use thee new card in something else in the near future.
It helps to download or backup the important information on memory cards to a DVD or a hard drive, just in case of failures.