Are you sure your file prefix is piointing to the right location? I.e. the location where your plugin and images are installed?
Page 6 of the instructions read:
If you copy the contents of "server" to /images/plugins/apex_super_lov_2_0
Then set the "File Prefix" attribute of the plug-in to #IMAGE_PREFIX#plugins/apex_super_lov_2_0/