The product affiliate system can only be activated for products using PayPal as their payment processor.   You can not combine the Secure Delivery affiliate system with 3rd party affiliate managers such as ClickBank or PayDotCom.

In Secure Delivery the affiliates column may display the following for each product:

• The "-" means that this product is not using PayPal as the processor and is not capable of utilizing the Secure Delivery affiliate system.
• The "No" means that the affiliate system is available, but is not currently being used.
• The "Yes" means that the product affiliate system is active for this product. Click the Yes link to visit the Affiliate Manager for this product.