Help with Show If expression for EnumList Ref column

[Lucinda_Mason]

IN(LOOKUP(USEREMAIL(), “Users”, “USER_EMAIL”, "DPT_NO”),{10})

I think the problem has to do with the DPT_NO column being an EnumList, Ref because other columns with different data types all work. What am I missing?

This works: LOOKUP(USEREMAIL(), “Users”, “USER_EMAIL”, "VIEW”)=“Simple”
and this: LOOKUP(USEREMAIL(), “Users”, “USER_EMAIL”, "PI_NO”)>15

Thank you.