Your LAST_MODIFIED_TIME is (presumably) a date-time, but you are comparing it with character values from your TO_CHAR functions. Leave all the dates as dates and it should work. Also, you can use "BETWEEN date1 AND date2" to catch dates inside a range.
No more Blub for me, thank you, Vicar.
I can't renounce my name. It's on all my stationery! And hinted in this tiny ad: