Target Display Mode on Yosemite

Hi!

Some years ago i bought Dr. Bott adapter to connect my playstation3 on my iMac and play. It always worked fine... Now, after some years i found again my old adapter, i connected all and it doesn't work. On my iMac i have Yosemite. When i connect Dr. Bott, i see a black screen, the signal led on Dr. Bott is red, but nothing appears. Any idea?