Pixel tracking problem in PHP

Let me first explain what i am trying to do:

step 1 : domain-a.com -> cookie is set using a redirecting P开发者_高级运维HP script(placed on domain-b.com) when a link to domain-b.com is clicked from this domain

step 2 : domain-b.com->main website -after a certain browsing user reaches domain-c.com

step 3 : domain-c.com -> when user reaches the thankyou page I placed an img tag with src = PHP confirmation script. (which confirms the cookie-placed on domain-b.com)

Everything is working like charm with Chrome and FF, but IE is not able detect or recognize the cookie inside the confirmation script on step-3.

I am not able to find any specific reason for this.

I will really appreciate if anyone can help on this.

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Try adding all three domains to your "trusted sites" in IE. If this fixes it, you know it's a cross-site/cross-domain policy issue, which IE can be really picky about. This may not present an immediate solution, but at least you'll know the cause.

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By default IE won't allow "3rd party cookies". Tools > Internet Options > Privacy Tab

Privacy http://img144.imageshack.us/img144/834/iepriv.jpg

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Sounds to me like a P3P issue.
If lowering your IE privacy settings gets this to work, then you need to declare your policy in the script header to make sure IE allows 3rd party cookies.
Run a search on p3p headers and you'll find plenty of guides.