change select_tag to select_tag"s"

app/views/admin/galleries/_form.html.erb

@@ -46,7 +46,7 @@
                   <!-- Tag -->
                   <div class="control-group">
                     <label class="control-label muted"><%= t(:tags) %></label>
-                    <%= select_tag(f, @module_app) %>
+                    <%= select_tags(f, @module_app) %>
                   </div>
 
                 </div>