Nginx & Crossdomain.xml?

Not too sure if anyone can help me with this since it's more 3rd party, but I recently installed an arcade script on my server using wordpress and it comes with a highscore script as well.

In order for the highscore script to work, it needs to communicate with the site that's sending the highscores. In order to do that, it uses the crossdomain.xml file

After asking for support from the plugin dev, this is what he told me:
> I've published the game "Click only red"on your site. That is the game that we use to test the score functions. But it doesn't work on your site.

I activated Firebug to check what's going wrong. I saw that there are some js error messages. Then I've deactivated all other plugins except MyArcadePlugin and MyScoresPresenter. Without success.

Then I checked the Network Timeline in Firebug and saw that the games don't try to to access the crossdomain.xml file. Hmm, that's really strange. I don't know the reason for that but it seems that Mochi games have problems with your domain or your server. :/

My server is currently running on nginx, which is usually the cause of a lot of things not being compatible or not responding normally since apache is more common I guess. Is there a rewrite rule for allowing sites to access crossdomain files or would it be something else?