Re: No result
Based on the numbers you quote (21,000 impressions), I'm going to assume you're advertising on the Display network and I hope I'm correct.
What's actually happening depends on so many factors--how you're targeting your campaign, whether or not you're using keywords, what kind of ads you're using, etc. I would recommend that you read the information at the links below. There's information there about how Display targeting works and that might help you answer your questions.
If you don't get the answer to your question(s) there, please do come back and post again. If you're able to give us a few basic facts around how your campaign is set up, we might be able to make some suggestions!
Google AdWords Top Contributor