Problem with date field with Oracle external database

Hi all,

i need to insert rows into Oracle external database. It's work fine with Native SQL instruction but i have a problem with date fields, the system goes back me an error.

My Oracle database is created like this :

CREATE TABLE ENT_ENTITE(

    ENT_No number(8) NOT NULL,

    ENT_DenSoc varchar(80) NOT NULL,

    TET_Code char(16) NOT NULL,

    ENT_CodeSiret varchar(14) NULL,

    ADR_Rue varchar(50) NULL,

    ADR_ComplRue varchar(50) NULL,

    ADR_Cedex varchar(10) NULL,

    ADR_CodePostal varchar(16) NULL,

    ADR_Ville varchar(32) NULL,

    ADR_CodePays char(32) NOT NULL,

    ENT_DtCessation date NULL,

    GRE_No number(6) NULL,

    DT_Mod date NOT NULL,

constraint PK_ENT_ENTITE primary key (ENT_No)            

)

In my ABAP code, if i fill the field 'ENT_DtCessation4 with the value 'NULL', the system return the following error :

"con=1(SAPEXTST.WORLD): ORA-01858: a non-numeric

character was found where a numeric was expected"

I don't know why.

Thansk for your help.

Regards,

Eric