SQL & PL/SQL

Hi,
I've a problem storing only time in date field value by oracle forms.
Actually i'm just updating time in a date field by oracle forms. but it is giving an error "not a valid month"
table column datatype is date.

my DB parameter are

SQL> SELECT * from NLS_INSTANCE_PARAMETERS;

PARAMETER                      VALUE
------------------------------ ----------------------
NLS_LANGUAGE                   american
NLS_TERRITORY                  america
NLS_SORT                       binary
NLS_DATE_LANGUAGE
NLS_DATE_FORMAT                DD-MON-RR
NLS_CURRENCY
NLS_NUMERIC_CHARACTERS         .,
NLS_ISO_CURRENCY
NLS_CALENDAR
NLS_TIME_FORMAT
NLS_TIMESTAMP_FORMAT

PARAMETER                      VALUE
------------------------------ ----------------------
NLS_TIME_TZ_FORMAT
NLS_TIMESTAMP_TZ_FORMAT
NLS_DUAL_CURRENCY
NLS_COMP                       binary
NLS_LENGTH_SEMANTICS           BYTE
NLS_NCHAR_CONV_EXCP            FALSE

Regards!