I just run afoul of some hard coded table names during the configuration of this addon. Please consider this line of code in admin/index.php:
$sql = "SELECT `config_name`, `config_value` FROM `roster_addon_config` WHERE `addon_id` = '".$addon['addon_id']."' ORDER BY `id` ASC;";
Sadly this table does not exist in my database, since I had to opt for the renaming of the basename of the tables, because I have a side-by-side installation of roster 2.0beta and 1.73. Since this is a legit choice and supported by the install procedure of Roster I am sure there is somewhere a variable you can use, so that you can mend this.
Sorry for the bother, but I think I am not the only one with this problem.