Application Express :: Default Value Date Picker Field

In a detail tabular form I am referencing a date picker field from the master form as default value.This is the situation in the detail form:

TABULAR FORM
Column Name: FECHAREGISTRO -- the field's name in the detail tabular form

Default Type: Item (application or page item name)
Default: P68_FECHAREGISTRO -- It's a field in the master form and also is Date Picker format
Reference Table Owner: SAMPEDRORIVEROS
Reference Table Name: BITACORAABOGADO
Reference Column Name: FECHAREGISTRO -- It's a date field in the database

At execution time I have the error:

report error:ORA-01790: expression must have same datatype as corresponding expression

I think it is because i must use to_date and to_char in order to change the datatype and i have tried using:

Default: to_date(to_char(:P68_FECHAREGISTRO,'DD-MON-YYYY'),'DD-MON-YYYY')

and in Default Type: PL/SQL Expression or Function but I get a different message at execution time:

report error: ORA-01722: invalid number.