Error trying to use Oracle Procedure

[sjoshi]

Hello All

I'm trying to use the DBMS_DATAPUMP.OPEN procedure but it keeps failing
with this message:

1) Exception Information
*********************************************
Exception Type: Oracle.DataAccess.Types.OracleNullValueException
Message: Invalid operation on null data
Number: -2502
Source: Oracle Data Provider for .NET
Data: System.Collections.ListDictionaryInternal
TargetSite: Int32 get_Length()
HelpLink: NULL

StackTrace Information
*********************************************
at Oracle.DataAccess.Types.OracleString.get_Length()
at
Oracle.DataAccess.Client.OracleParameter.GetBindingSize_Char(Int32 idx)
at Oracle.DataAccess.Client.OracleParameter.PreBind_Char()
at Oracle.DataAccess.Client.OracleParameter.PreBind(OracleConnection
conn, IntPtr errCtx, Int32 arraySize)
at Oracle.DataAccess.Client.OracleCommand.ExecuteNonQuery()
at DAO.OracleConcreteFactory.ExecuteNonQuery(DAORequest request) in
F:\Sunit\CSharpFiles\Scripts\DAO

The procedure signature as per Oracle docs is:

DBMS_DATAPUMP.OPEN (
operation IN VARCHAR2,
mode IN VARCHAR2,
remote_link IN VARCHAR2 DEFAULT NULL,
job_name IN VARCHAR2 DEFAULT NULL,
version IN VARCHAR2 DEFAULT 'COMPATIBLE'
compression IN NUMBER DEFAULT KU$_COMPRESS_METADATA)
RETURN NUMBER;

In code I do this:

_conRequest.Command = "DBMS_DATAPUMP.OPEN";
_conRequest.CommandType = CommandType.StoredProcedure;
_conRequest.AddParameter("operation",OracleDbType.Varchar2, "EXPORT",
ParameterDirection.Input);
_conRequest.AddParameter("mode", OracleDbType.Varchar2, "SCHEMA",
ParameterDirection.Input);
_conRequest.AddParameter("remote_link", OracleDbType.Varchar2,
OracleString.Null, ParameterDirection.Input);
_conRequest.AddParameter("job_name", OracleDbType.Varchar2, "EXP_TEST",
ParameterDirection.Input);
_conRequest.AddParameter("version", OracleDbType.Varchar2, "LATEST",
ParameterDirection.Input);

_conRequest.AddParameter("jobhandle", DBDataType.DBInteger, null,
ParameterDirection.ReturnValue);

I think it fails when trying to evaluate the remote_link parameter. Any
hints are greatly appreciated.

Sunit