Anda perlu mendapatkan pembaca dari parameter, bukan dari perintah.
Jadi, alih-alih
Dim reader As OracleDataReader = rvCmd.ExecuteReader()
Anda membutuhkan:
rvCmd.CommandType = CommandType.StoredProcedure
rvCmd.CommandText = "getallprodpckg.get_allcust"
Dim qrySerial3 As New Oracle.DataAccess.Client.OracleParameter(
None, OracleDbType.RefCursor, ParameterDirection.ReturnValue)
rvCmd.Parameters.Add(qrySerial3)
rvCmd.ExecuteNonQuery()
Dim cursor as OracleRefCursor = DirectCast(qrySerial3.Value, OracleRefCursor)
Dim reader As OracleDataReader = cursor.GetDataReader()