If you have an older copy of the original VDL 2.5 DVD (prior to 2012) that DVD shipped with a Vise installer. If you attempt to run the installer, you'll find that it spins for a bit, then just quits. This installer does not work on Macintosh operating systems greater than 10.5+ (Leopard+) and is no longer supported.
Instead, you must get a library replacement/update which comes with a current download + installation process.