PowerEdge 2900 - PSU problem - Simple Question

Hello,

I am new to the server world and have a simple question that can't find an answer to. We decommissioned our 2900 last fall and it was running fine no issues we just upgraded to 2012 server and got a new server to run that. One of our smaller locations could benefit with the old server so we want to get it set up for them. So I plugged in the Power supplies (we have 2) and there is green light on both power supplies where the electrical icon is showing green but that's it. Nothing happens when you press the on button. I think another green light needs to be on to show the PSU is working correctly - is this correct? Also does this mean we need new power supplies?

Any information is greatly appreciated!