I found this at an ORACLE SQL reference site this is the correct format for an ORACLE date. ORACLE uses - not \.

DATE datatype
A standard Oracle datatype used to store date and time data. Standard date format is DD-MMM-YY, as in 01-JAN-89. A DATE column may contain a date and time between January 1, 4712 BC to December 31, 4712 AD.

Try this maybe it will work. Otherwise you may have to TO_DATE the field as it is passed to ORACLE this will slow down the system though as it by passes all indexes.