I'm confused.
"Cascading combo boxes work but when I try to pick a date, I get this error in the code."
How can they work but produce an error? Anyway, not enough info on the combos to zero in on the issue but I suspect one or more of the downstream combos has a rowsource property that is looking at the wrong column in the combo that precedes it. Put a break point on the me.recordsetclone line and when it stops there, mouse over the variable and see what it contains. I suspect you're referring to the wrong column of the "upstream" combo in the rowsource of the downstream combo(s).
EDIT - Posted before I saw your update. Will have to review and probably am done for the night. Site is acting up here, and it's getting late.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.