You mentioned that you leave links all over the place, but have you personally invited any users to chat? A member of the community in active in did just that when I was a new member. Now a day doesn't go by that I'm not in that room.

That will help get people into the room, but once they're there, they need a reason to stay there.

You mentioned in the comments that it is a Stack Exchange Site, so the next part of this answer may be a bit specific and I apologize to future readers in advance.

Stack Exchange chatrooms natively support adding RSS feeds to the room. These feeds can be posted as chat messages. You could add a "Newest Question" feed. Links to SE sites are one boxed so they look pretty, but you could also add feeds from any RSS feed that is relevant to your community. This gives your chat users something new to talk about all the time. Having something to talk about is half the battle of having an active chat room.

You mentioned that you leave links all over the place, but have you personally invited any users to chat? A member of the community that I'm active in did just that when I was new. Now a day doesn't go by that I'm not in that room.

That will help get people into the room, but once they're there, they need a reason to stay there.

You mentioned in the comments that it is a Stack Exchange Site, so the next part of this answer may be a bit specific and I apologize to future readers in advance.

Stack Exchange chatrooms natively support adding RSS feeds to the room. These feeds can be posted as chat messages. You could add a "Newest Question" feed. Links to SE sites are one boxed so they look pretty, but you could also add feeds from any RSS feed that is relevant to your community. This gives your chat users something new to talk about all the time. Having something to talk about is half the battle of having an active chat room.