Configuring RTMPS with a self-signed certificate

I have configured FMS 4.0 to do RTMPS on port 443. To test it, I created a self-signed certificate and then imported the certificate as an authority in my browser (Firefox). I don't want to go and get a real certificate until I can verify that FMS is able to do what I want it to.

I included the path to the certificate and the private key in Adaptor.xml in <install dir>/conf/_defaultRoot_/

That's the only file I have modified.

My ActionScript looks something like this:

var nc:NetConnection = new NetConnection();
nc.addEventListener(NetStatusEvent.NET_STATUS, onNetStatus);
nc.proxyType = "best";
nc.connect("rtmps://blah");

In the NET_STATUS handler I always get the following error: NetConnection.Connect.CertificateUntrustedSigner.

I don't understand why I am getting this error as I have installed the certificate as an authority in my browser.

Any thoughts?

Thanks