Can't get into Dark room through the Sacrifice Room

[Bisaishi]

I am currently playing Challange #2 and had a good opportunity to torture myself in the Sacrifice room. I ran into the spikes like over 30 times and the Dark Room wouldn't spawn. I got the two Key Pieces for Mega Satan and wanted to fight him.

Why is it the Dark Room won't spawn?

I read that the Dark Room is unlocked by beating Satan 5 times, which I haven't done yet. Is that the reason?

Do one only can be teleported to the Dark Room from the Sacrifice Room by unlocking the Dark Room before?

Or is it that you can't get into the Dark Room while playing a Challange?

[RedSage]

You can't go to Dark Room through sacrifice rooms in challenges where the end goal isn't Dark Room. The end goal of Challenge 2 is mom's foot, so that's why it won't work.

[Bisaishi]

Originally posted by RedSage:

You can't go to Dark Room through sacrifice rooms in challenges where the end goal isn't Dark Room. The end goal of Challenge 2 is mom's foot, so that's why it won't work.

Thank you :3