Im using my Sony Xperia M (jelly bean 4.3) with my chromecast. For a while now I've been looking for ways to mirror my android screen to my TV as my phone doesn't support the chromecast screen mirroring feature and I thought I found the answer with Firefox using your mirror tab feature, but the only problem is when I activate the mirror tab feature and select my chromecast, I just get a blank black screen on my Tv. My phone says it's mirroring as it gives me the option to stop mirroring, but nothings coming up on the TV.

Any ideas on how to fix this problem?