Comments and Ratings don't work

The plugin is using the page.php template of your theme by default. If the page template of your theme doesn’t include a comment form/ listing it can explain it doesn’t work.

To solve this you can create an ideastream.php template within your theme copy the page.php markup of your theme and include in it the comments template tags.

https://github.com/imath/wp-idea-stream/wiki/Ways-to-customize-the-plugin-from-your-theme