It is typical of google ads to not offer any sort of ad, other than Community Service, immediately after adding the link into your site. The bot has to comb your website looking for keywords 'before' it can display any relevant ads. Also, I would like to offer up a word of caution, don't trust all the Adsense module add-ons.
I downloaded a supposed module to display my google ads from another forum andd basically it worked....but it would not allow the input of
my account number, so the original guy who coded it was getting the credit for impressions and clicks.
Therefore I made my own...which is extremely easy. Simply through administration select Modules->Site Modules. Then you will select 'New', give it a title and simply cut'n paste the google adsense code into the 'content' box. Save it and your good to go. My only word of caution is to turn off any sort of wysiblahblahblah editors, because it can mess up teh coding.
Here is the coding for a simple 120X600 text ad:
<script type="text/javascript"><!--
google_ad_client = "YOURACCOUNT#HERE";
google_ad_width = 160;
google_ad_height = 600;
google_ad_format = "160x600_as";
google_ad_type = "text_image";
google_ad_channel ="";
google_color_border = "CCCCCC";
google_color_bg = "FFFFFF";
google_color_link = "000000";
google_color_url = "666666";
google_color_text = "333333";
//--></script>
<script type="text/javascript"
src="http://pagead2.googlesyndication.com/pagead/show_ads.js">
</script>
Just don't forget to sub in your account number, probably begins with a "pub" and you should be good to go. Hope this helps anyone else looking to add them to your site. Also, it's real easy to force the module to be active on every page...which is a beaut for the type of ads displayed by google.