Why do I see 'Banner deleted' message in a transaction?

The "Banner deleted" message may occur in a transaction in the following cases:
 
1) The transaction was added manually through the merchant panel or imported/uploaded from a .csv file
2) The campaign id was explicitly  defined in the sale tracking code
3) A simple affiliate link (not a banner) was used  to get to the merchant's e-commerce page
4) The product purchased matched a different campaign than the banner used by the customer to land on your site who accomplished the purchase
Example:
Customer Z  clicks banner A that belongs to campaign A. But he purchases product B that is defined in campaign B.
 
5) The banner used by the customer has been already deleted from Post Affiliate Pro (Post Affiliate Network)
 
 
 
How to find out, if the transaction was added manually or imported/uploaded from a .csv file?
At Campaigns > Campaign manager  click "Edit view" above the grid listing the transactions, check in  the "Log group" option, rename the view name and click Save. 
 
The "Log group" column will appear. If there is no log group id next to the transaction then the transaction was added manually or imported/uploaded from a .csv file
 
 
How to find out, if the campaign ID was explicitly defined in the sale tracking code (or hidden image tracking pixel)?
 
If you had the debug logs turned on concerning sales/leads  at Configuration > Event Logging
 
then the particular debug logs can be checked for the particular transcation via  "Log group".
At Campaigns > Campaign manager  click "Edit view" above the grid listing the transactions, check in  the "Log group" option, rename the view name and click Save. 
 
The "Log group" column will appear. 
If you see next to the transaction a Log group id   (A-xxxxxxxx), then you may click the 'magnifier' icon next to it and you would see the debug logs (how the transaction was tracked and saved) with regard to the particular transaction.
 
When the logs appear and you hover the first line, you will see the exact JSON request that was posted to Post Affiliate Pro (Post Affiliate Network). In that request you can check if there is any value for "c" - campaign. 
As you may see in the screenshot above, there is "c":"a501f73b"  -- it means, that in the sale tracking code (or in the hidden image tracknig pixel) the "a501f73b" was used in the setCampaignId('a501f73b')  (or CampaignID="a501f73b")   parameter.
 
The above mentioned fact is proved also by the following 3 log lines:
 
Recognizing campaign started
Trying to get campaign from request parameter
Checking campaign with Id: a501f73b
 
That's it!