"Why No Earning for Some Clicks? - Google Adsense Question | Legitimate Online Money"

You certainly have noticed that you have clicks reported, but no revenue? This confused me for some times and I had started to suspect if there are adsense advertisements on my site of $0.00 in addition to those public service advertisements! Now, I found the reason and relieved!

This phenomenon may be due to one of the following:

1. Allowed Sites setup
   
   The Allowed Sites feature allows you to specify a list of sites where ads from your account may be displayed. This feature is provided so that you can ensure no other publishers are using your adsense codes to adversely effect your account. You can list all your sites where you are using your adsense codes. The advertisements resulting from your code but not in the Allowed Sites list of your adsense account will be ignored. If you're using this feature, you'll need to make sure that you've listed all sites where you'd like to display your AdSense ad code.
   
   To check if this is the case, log into your account and visit the 'Allowed Sites' page under your AdSense Setup tab. If the radio button 'Allow any site to show ads for my account ' is populated, you're not being affected by this issue, and you should continue to #2 below.
   
   However, if 'Only allow certain sites to show ads for my account' is populated, review the list of sites in the box below -- are all the sites you own listed in this box? If the answer is 'no', you won't be credited for clicks on the missing sites. Please be sure to add all of the sites where you'd like to display your AdSense ad code.
   
   Amusingly, there are some confusion among publishers who have entered the sites of advertisers they'd like to see on their pages into the Allowed Sites list. It's not possible to request ads for a particular page - the sites you enter into this box can only be sites where your ads can be placed.
   
2. Invalid clicks
   
   It's possible that you have some clicks that our monitoring system has considered to be invalid. Adsense monitors all clicks and impressions on Google ads for any activity that may artificially drive up an advertiser's costs or a publisher's earnings. Any clicks that the system considers invalid will still appear on your 'Overview' page, under the Reports tab. However, because advertisers aren't charged for these clicks and impressions, it won't show the earnings for this activity. If you're concerned about suspicious activity in your account, you are suggested to check your site's logs and report to adsense.

Rest assured that AdSense accounts are properly credited for all clicks and impressions that are considered to be valid. Adsense posts your finalized earnings for a given month on your 'Payment History' page during the first week of the following month.