Sessions not Associated with the Correct Source
You may notice that the sessions in your reports are being associated with the wrong sources. This is often caused by common mistakes in implementing the tracking code on your site.
Untracked Landing Pages
For a session to be attributed to the correct source, the landing page for the session must have the tracking code properly installed. If the code is not installed correctly, it is common for a session to appear as direct in the Analytics system, since the first tracked page on the site registers a referral from the previous untracked page. A large number of direct users usually indicates untracked landing pages.
Improperly Tagged Links
If you are using autotagging, Google Analytics automatically appends the gclid (Google Click ID) parameter to the end of the destination URL. It interprets source, campaign, medium, term, and content information from this ID as long as autotagging is enabled and the landing page has the tracking code properly installed.
If you are not using autotagging, it is possible that source information is not being associated with the appropriate sessions because of improperly tagged links. Please use the URL Builder to ensure that the destination URLs you create are properly tagged.
Ecommerce transactions: crossing between domains
If you require that users cross domains during the checkout process on your site, you must ensure that you have added the necessary lines to your tracking code. Please refer to the FAQ on tracking 3rd party shopping carts for more information. If you do not add these lines to the tracking code, the referring-source information gets dropped when a user navigates between the domains, and the transactions in your reports may be attributed to direct sessions instead of CPC or organic traffic.