Do I need to be approved as an affiliate for each merchant?

In order for your commissions to be tracked, you must be an approved affiliate on each merchant's programme. If you haven't been approved for any merchants included in the search, contact the relevant network directly to ask them to look into why your approval hasn't gone through. They normally need to see a link to your site, and will check to see if it is relevant to the merchant's target audience.

Here's a list of all the current merchants and their networks:

Ebookers - TradeDoubler
On the Beach - AffiliateWindow
Thomas Cook - Affili.net (includes: Airtours, Flexible Trips, Manos, Thomas Cook)

If you're not approved on any of these programmes, QuickStart will still work, but you'll need to remove the unapproved brands or commissions will not be tracked on any unapproved programme.

Find out how to do this here:
http://help.distributetravel.com/entries/21218622-how-can-i-choose-which-brands-are-included-in-the-search-results