I suspect that will be woefully inadequate. It may be the cause of your failure to get the strip working. 500mA @ 12V is enough for around 25 rgb leds.
But referring back to your original post, I realise there are two pieces of information you didn't tell us. How many leds per metre (30, 48 or 60)? How many metres long is the strip? (That eBay page does not seem to tell you how long the strip is that you are buying. That would have rung alarm bells for me and I would not have purchased from that seller).
For a 5m strip with 60 leds per metre, you would need a 12V PSU with at least 6A capacity, ideally 7.5A for safety.