Why will nobody accept me into heroic raid?

So I’m currently a healer on emerald dream with an ilvl of 466 which I’ve asked a couple people saying shoudl be fine for a heroic raid. I’m just trying to get the AOTC achievement before season is done with and am getting frustrated that I keep getting declined. I’m guessing they can see that I’ve never done the raid before or am I mistaken by my gear level?