Sales are not tracked, what is wrong?

If your Post Affiliate Pro does not track sales, then please check, if you have inserted the sale tracking code into your "thank you page". The code should be inserted somewhere between HTML tags <body> and </body>.
Some exact points to follow are listed here:

My sale tracking code is OK, but sales are not tracked
You have probably forgotten to insert the click tracking code into the landing page (destination URL of your banner). Sales cannot be tracked without click tracking. When a visitor clicks on the banner, he/she is redirected to your landing page. There should be a click tracking code, because it also creates a cookies, where PAP saves data about affiliate (or PAP remembers the IP address). When the customer makes a sale, then PAP loads data about affiliate from cookies or search the IP address. If the clicks are not tracked, PAP can not recognize, what affiliate should get a commission.

Check your plugins
If you are using some payment gateway, check the Plugins section out to see if there is a plugin for it. If there is one, check it out if it is activated, and configured properly.

Check your Fraud protection settings
The settings for Fraud protection can prevent some sale commissions from being saved. Check these settings out to see if all is set correctly.
Check your Settings
Go to your merchant panel and go Start menu -> Configuration -> URL parameter names. If you do not see any values here that may be the reason why sales (or clicks) are not tracked.
Default values are:
Affiliate ID / referrer ID: a_aid
Banner ID: a_bid
Campaign ID: a_cid
Data 1: data1
Data 2: data2
Destination URL: desturl
You are using frames on your page
If you are using frames on your page, do not insert tracking code into your main frameset page. Insert it only to some of the frames (footer, or sidebar for example).