the following code in a SQL interrogation always return "0-12"

IIF( (HOUR( TTOD( Table1.datecreation)) >=0  AND HOUR( TTOD( Table1.datecreation)) <= 11), "0-12", IIF( (HOUR( TTOD( Table1.datecreation)) >= 12 AND HOUR( TTOD( Table1.datecreation)) <= 15), "12-16", "16-24")) as HourBlock

Data contains hours in all the range 0-24. So I should have some "12-16" and "16-24"

You guys see something that I don't?