Google Analytics UTMZ campaign is overwritten by direct?

i use Google Analytics with sub-domains and an iframe. The landing page on sub.mydomain.com contains an iframe with a registration form on www.mydomain.com.

1. The user clicks a banner sub.mydomain.com/landing?utm_source=so1&utm_medium=dis&utm_campaign=xe1&utm_content=re1

2. On the landing page, the registration form and the thankyou page this javascript code is used

   var pageTracker = _gat._getTracker("UA-xxxxxx");
   pageTracker._setDomainName(".mydomain.com");
   pageTracker._setAllowHash(false);
   pageTracker._setAllowLinker(true);
   pageTracker._trackPageview();
   

   on the landing page the iframe is loaded in the following way

   
   var iframe = document.getElementById('register_iframe');
   iframe.src = pageTracker._getLinkerUrl('http://www.mydomain.com/register.html');
   

3. The cookies on sub.mydomain.com and the registration iframe from www.mydomain.com both contain _utmz with utmcsr=so1|utmccn=xe1|utmcmd=dis|utmcct=re1

4. After submitting the the ajax form in the iframe the request for the thankyou page and some new javascript files still transfer the correct set __utmz cookie

5. the javascript from 2. on the thank you page then requests the __utm.gif but is now transferring .utmcsr=(direct)|utmccn=(direct)|utmcmd=(none) and the cookie on .mydomain.com is set to .utmcs开发者_Python百科r=(direct)|utmccn=(direct)|utmcmd=(none) too

As far as i know the ga code shouldn't overwrite a direct set source with direct or something else.

Thanks for any help

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If Google Analytics Cross Domain Iframe Tracking is implemented as above, it should work.

I changed 2 things

1. I forgot to set in the iframe tracker code pageTracker._setAllowLinker(true);

2. I used on the landing page, that was hosted on a subdomain pageTracker._setDomainName("sub.mydomain.com"); i changed that to the same as on the main page in the iframe pageTracker._setDomainName(".mydomain.com");

As i understood the documentation that was not necessary, so don't know if that had an effect.