SELECT DISTINCT trunc(settle_dte) FROM heloc_tracking WHERE settle_dte > TO_DATE('25.7.2001','DD.MM.YYYY') AND settle_dte < TO_DATE('27.7.2001','DD.MM.YYYY') ORDER BY trunc(settle_dte)

Or it could be yelling about the ORDER BY column not matching the SELECT? Wrap both in a trunc() and try again.

- Chris