Conversion tracking via thank-you page visits is more reliable with traditional freestanding ecommerce software that you'd install and configure on your own server, which can control the entire purchase process from start to finish and can therefore make sure buyers reach a thank-you page after checkout. E-junkie spares you the technical hassles of installing and managing your own ecommerce sofware, but easy and accurate conversion tracking is one of the tradeoffs you sacrifice for our ease-of-use.
E-junkie depends on third-party payment processors to handle checkouts, and we cannot always instruct those services to auto-redirect buyers to a thank-you page after completing checkout on the processor's site. Depending on the payment processor(s) you're using and what type of products you're selling with our system, conversions may not be accurately trackable at all. The differences in post-checkout behavior among the payment processors we support are explained in the "IMPORTANT - Notes on Conversion Tracking" section at the top of our Tracking help page:
If all of your products are downloads, which buyers would need to obtain from your standard E-junkie-generated thank-you/download page, then buyers have an incentive to visit their thank-you page at some point, where their conversion could be tracked.
If you have any products that are not downloads, and if you are using PayPal, Google Checkout, or TrialPay, those may not track conversions accurately because the buyer has no reason to view a thank-you page at any point, and those payment processors cannot auto-redirect buyers to any thank-you page after checkout.
If you are using Google Checkout as your sole payment processor, then you can track conversions directly from GC by integrating that with Google E-commerce Tracking. This is what we recommend for sellers who are serious about tracking every conversion if they are selling any non-download products. You can combine this with Authorize.Net if you want a card-based direct payment option, as we control the checkout behavior in that case and do auto-redirect buyers to a thank-you page for those purchases.