Blank JOptionPane.showMessageDialog under Linux


I developed my application under Windows XP
(NetBeans), but it will run under Linux (exactly Fedora 9).
I have problem. Sometimes I need to show
message dialog to inform user. But, unfortunately
sometimes my message dialogs are just blank
(there are window with title, icon but no text, not buttons).
Under Windows, everything seems to work correctly.
Do you have any idea, how to fix this?
Thanks in advance for your help.