I'm having trouble with the Building a Geodatabase tutorial. "Failed to update domain. Item relationship already exists." Why is this happening? How do I solve this issue?

[AudreySerfes]

I'm having trouble with the Building a Geodatabase tutorial. When finishing exercise 3, an error screen pops up. It reads: "Failed to update domain. Item relationship already exists." Why is this happening? How do I solve this issue?

Thanks,

Audrey