flash AS3 navigateToURL : link changed

Hi everyone,
I just created a small .swf for Flash where a click triggers an navigateToURL to a given url.
It is embeded on an html page in a domain where a WordPress blog is installed. The page is in :
[b]https://www.myDomain.com/TestDirectory[/b]
On the same html page I put a classical html link with the same endpoint url. It works for the html link BUT for the navigateToURL I see something strange :
This given url (to addthis.com) :
[i]https://api.addthis.com/oexchange/0.8/offer?url=https://www.myDomain.com/TestDirectory/testPage.html[/i]
… is replaced by :

[i][b]https://www.myDomain.com/TestDirectory[/b]/https://api.addthis.com/oexchange/0.8/offer?url=https://www.myDomain.com/TestDirectory/testPage.html[/i]
??
As you see, the url of the page is added at the beginning and of course, it does not work …

Frankly, I don’t understand …
Any idea ? ??
THANKS