It's been so long I don't remember. Do you have your Analytics check box ticked to show Google AdSense?

I think it was a link to the analytics page that you can link them. Go to your Analytics account, click Admin, Click All accounts, select the Account Name, click Data Sources > Adsense. You can link your accounts there.

Second, if you're using async analytics code or '_setDomainName' to restrict cookie to a single domain, you have to have following code before every ad code.

<script>
window.google_analytics_uacct="UA-0000000-0";
google_analytics_domain_name="www.example.com";
</script>

@levo: Thank you very much! It is incredible how well google managed to hide this option!
I never found this and there is no info on this available (that can easily be found ... googling for it anyway).
Thanks a lot!

edit: I celebrated too early...
The integration seems to be possible for one account only. Another account in analytics does not seem to be linked. I get the request to link it in adsense, but I can't find where to do this in the adsense page.
any clues?

Did you put the extra code in your second site?

it is not a site, it is an account.
I managed to add the code to all the sites of the 1st account,
but i cant for this 2nd account because google asks me to link the account with adsense first

I'm unclear whether you're trying to link two analytics accounts to one adsense, or two adsense to one analytics, but I don't think either one is possible. The Analytics account and the AdSense account are usually the same Google account.

I've a similar problem. When I first joined google long, long ago it would not allow me to use the same email for Adsense and Analytics - I have one email for Adsense and then another for Webmaster Tool, Merchant Centre, Analytics etc.
It's a pain and ideally I'd love to merge the two together.

ok thanks, looks like not all my sites can have the integration.
A few other questions: I have set this up for a couple of sites now, but after 4 days I have noticed that estimated income in analytics is less than half then income in adsense. When clicking the button in analytics where the differences are shown, they still do not match up with the real adsense earnings
I have checked support.google.com/adsense/bin/answer.py?hl=en&answer=55613 but none if the items seem to be relevant to my case or can explain the size of the discrepencies.
Anyone any thoughts on this?
Is there a way I can check on which pages my adsense code for a certain link block is being shown? I am pretty sure it doesn't appear on any other site, but you never now...

4 days into this I only seem to be having 1 site were the integration was succesfull, the other sites still show that I should link adsense and analytics. The site that does show it is my biggest site in earnings. Could this be the reason?

Are you using the extra code I've posted. If you've 2-3 ads on page, you have to add the code before each adsense code. Each adsense code nulls 'window.google_analytics_uacct'

oh! did not realize this, but the instructions clearly stated that the code should go just before the closing header tag?

Not the analytics code itself, but you should add 'window.google_analytics_uacct' and 'google_analytics_domain_name' in front of every adsense unit. Instructions say to put them once, but then it only tracks the first ad unit, and you end up with discrepancies.

@levo: thank you very much for your help! it seems to be working as it should now.
It is unbelievable that this information is nowhere available on google's own website (I could not find it anyway), so I am wondering how you figured this out.

Unofortunately also is that only 1 domain is showing the ads in analytics, the other ones I linked are still showing I should link them.

edit: after rereading your previouus post

Second, if you're using async analytics code or '_setDomainName' to restrict cookie to a single domain, you have to have following code before every ad code.
<script>
window.google_analytics_uacct="UA-0000000-0";
google_analytics_domain_name="www.example.com";
</script>

I am wondering if I should always also add the domain name, or only when I use url channels?
At the moment i only have the UA code, could this explain why only one domain is showing?

It is unbelievable that this information is nowhere available on google's own website (I could not find it anyway), so I am wondering how you figured this out.

I too had the discrepancy problem between Adsense and Analytics. There were a couple of mentions of adding extra code just before the Adsense code, so I figured maybe I had to add them before each one... and it worked. I've also tried many combinations, and I suggest to just add that code before each adsense code and it will work.

AFAIK, google_analytics_domain_name is required when you're using _setDomainName in Analytics code, window.google_analytics_uacct is required when using the async Analytics code. I use both of them for each adsense block.