A lot of advertisers tend to think in these terms. People think I bought media, people are looking at my ads, they are clicking on them as well, my sales should go up. Really? Why? In most of the cases it will or should go up, but sometimes it will not. Why? Have you checked your website analytics, i.e. how is the consumer flow? Are there are places where people are dropping off a lot? If yes, that thing needs to be fixed. For example: if consumers are not flowing through after step 3 in the process, then there is something wrong for example is the next button not working or is the next step that you intend the consumers to take not clear enough. The funnel below shows it all…
Net net the most important thing is to track as much as you can, to find out where the consumers are bailing in the checkout process and try to fix that. It might not be an easy fix and it can take a few tests to figure out the exact reason and then you can have your Advertising "$" working for you i.e. generating "$$$".
This is a very common problem seen with e-tailers who have a pretty complex checkout process which could involve more than a simple 5 step process. I have personally seen processes which are over 40+ steps and if there is no web analytics is place, then the advertising team is blind to where consumers are dropping off.
The solution is available fairly easily - use tools like Google Analytics, Webtrends, Omniture - you can define the complete consumer flow, look at visually where people are clicking or missing out on clicking, and then act. It's a circle which goes on - track, test, implement, track again :)