Hover buttons use two JAVA classes called fphover.class and fphoverx.class - Without these you will not be able to see the hover buttons.
If a browser hasn't seen a hover button before then it downloads the two files to it's JAVA directory and everything is fine, However you do need to have those two files in the root of your web page for this feature to work.
Hope that helps - If you have any other problems let me know and I can email the files other with some more detailed instructions.
Gary.