Call Oracle function in package in vb.net - vb.net

Question

I just begin with Oracle. I read lot of post and ... I don't find where is my mistake
I've a function in package PKG_GETOBJ
FUNCTION GetNewID(sReference IN VARCHAR2) RETURN NUMBER
IS
NewCtpVal NUMBER;
BEGIN
UPDATE TABLE set VALUE = (VALUE + 1) WHERE Field= sReference RETURN VALUE INTO NewCtpVal;
return NewCtpVal;
END;
and here how I try to call it:
Dim con As OracleConnection = GetConnexion()
con.Open()
Dim cmd As New OracleCommand With {.Connection = con}
'PKG_GETOBJ.GETNEWID('ID_OBJECT');'Sample calling in SQL with success
cmd.Parameters.Add(New OracleParameter With {.ParameterName = "sReference", .OracleDbType = OracleDbType.Varchar2, .Value = "ID_OBJECT", .Direction = ParameterDirection.Input})
cmd.Parameters.Add(New OracleParameter With {.ParameterName = "NewCtpVal", .OracleDbType = OracleDbType.Double, .Direction = ParameterDirection.ReturnValue})
cmd.CommandText = "PKG_GETOBJ.GETNEWID"
cmd.CommandType = CommandType.StoredProcedure
cmd.ExecuteNonQuery()
For Each p As OracleParameter In cmd.Parameters
HelperJournal.WriteEntry("PKG_GETOBJ " & p.ParameterName, If(p.Value Is Nothing, "null", p.Value.ToString))'Write in file
Next
con.Close()
con.Dispose()
My problem is NewCtpVal is empty, then I Database I've a number value...

Answer 1

Finnally I found a way...
Public Function GetNewId() As Decimal
Dim retval
Using con As OracleConnection = GetConnexion(),
cmd As New OracleCommand With {.Connection = con}
cmd.CommandText = "PKG_GETOBJ.GETNEWID"
cmd.CommandType = CommandType.StoredProcedure
Dim prm = New OracleParameter("returnvalue", OracleDbType.Decimal)
prm.Direction = ParameterDirection.ReturnValue
cmd.Parameters.Add(prm)
Dim prm1 = New OracleParameter("sReference", OracleDbType.Varchar2)
prm1.Direction = ParameterDirection.Input
prm1.Value = "ID_OBJECT"
cmd.Parameters.Add(prm1)
con.Open()
cmd.ExecuteNonQuery()
retval = cmd.Parameters("returnvalue").Value.ToString
End Using
Return retval
End Function