According to the plugin description, you also need the Whacko Sound Patcher to make it work. If you haven't done so, download it and install it after you installed the sound plugin. You can download it from http://www.msgplus.net/pluginsdb/down/pafiledb.php?action=file&id=59.
Note: the plug-in was made for Plus! 2.20, and the patch is to make it work with Plus! 2.50. I cannot guarantee you it will work on Plus! 3.
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