RCA splitter problems?

You are plugging the inputs and outputs into the wrong places...

And that Y cable may be incorrect unless you bought additional RCA cables. The AV-OUT connector the X-Box should be female. This means you plug a male RCA into them and there should be two available female RCAs. You are splitting the source - the X-Box.

The using the male to male you were using before to connect to the TV, that leaves you needing another set of male to male cables to connect to the Dazzle... then the Dazzle connects using USB to your computer.

Make sure you are connecting to the Dazzle's INPUTS not the outputs. They are marked... and the inputs should be on the front of the Dazzle.

It's called a "Y" adapter and it's used for audio. Audio is pretty straightforward. You can combine two audio feeds into one, or feed one audio signal to two devices. There are some concerns about impedance matching, but nothing catastrophic under most conditions.

But RCA for video is completely different. Video is a very complex signal, and trying to combine two videos into one, well, it just DON'T work. Period. You can potentially feed one video to two devices, but even that causes a something of a problem in that the video will be about half brightness, and the devices may or may not lock up to it.

Someone else stated the only fix available, and that's to use a video distribution amp (DA). There are some cheap ones out there, maybe check with Radio Shack, but even then it still costs some bucks.

You need an active video distribution aplifier. You cannot passively split video signal.