Can't "double post" on "Artist missing links" thread

I was about to post another reply on the "Artists missing links" thread (because I found another artist missing links) but, when I tried to, I got a message saying that I couldn't double post on a thread and that I had to edit my previous message instead. I didn't do that because I didn't know if someone would see that I've edited the reply.

So this is what I did and what happened:
- I deleted my previous message because I thought that then I'd be able to post.
- When I tried to post a new reply, I still got the "You cannot double post" message.
- I tried to post anyway (with the new information I had to share).
- The new reply didn't show up on the thread.

So... I don't know how to proceed.

From now on, watch should I do if I have another artist's missing links to share? Should I just edit my previous post on that thread? Or... something else?

I'd appreciate some clarification on this.

P.S.: This is the link that I wasn't able to post = Kourui, Twitter, Gallery