vba functions are frequently different from worksheet functions with the same name.
MOD is one example, I guess DateValue behave differently too.
The worksheet function DateValue seems to be happy dealing with hours >24, the vba function DateValue doesn't.
You could stick with the worksheet function by trying the likes of:
Evaluate("DateValue(""" & test.Value2 & """)")
or
yy = Evaluate("DateValue(""" & test & """)")
or longer:
yy = Evaluate("DateValue(""" & test & """) + TimeValue(""" & test & """)")
If the quotation marks are in the cell and show on the worksheet then perhaps:
yy = Evaluate("DateValue(" & test & ") + TimeValue(" & test & ")")

I'm not at all sure whether you'd have to:
yy = Evaluate("DATWERT(""" & test & """)")