have you added content of styles.txt file to the global.css stylesheet of the theme ?
what is your forum url ?
Try hard refreshing, press ctrl+f5, if its still the same, keep clicking ctrl+f5, if it dosen't work, check if you added the styles in styles.txt, just what .m. said.
I have this same problem, i added to my style.xml content of styles.txt and installed shoutbox, and i have no shoutbox..
^ {$dvz_shoutbox} should be added to
index template of your theme
[and you should remove it from
global.css of the theme]
see also
templates related guidance here