wordpress_mu, xmlrpc and flickr – not working

Hey, I just installed wordpress_mu and wanted to use flickrs “Blog This” feature with one of these wordpress_mu blogs. But it doesn’t work, flickr gives the following error message:

The endpoint you entered was not correct.

But the endpoint is correct. I can enter the URL into my browser and it gives me:

XML-RPC server accepts POST requests only.

And all 3rd party blogging applications work well with the URL too so I guess xmlrpc.php works actually well. Except for flickr.

Now I’ve read through a couple of threads at flickr and here but I couldn’t find anything concerning wordpress_mu. I’ve tried the htaccess thing and I’ve tried several ways to write the URL (with http:// and without it, etc). I guess this is a specific wordpress_mu / flickr issue ?

Any ideas ?

John