AbleCommerce Shopping Cart Software

I'm trying to convert the basket into the order with a custom payment method.
However, the checkoutresponse.success is false. Is there anyway I can see which part is failed?

For the custom payment method, I only create a new method without assigning a gateway.
Is it an issue in this case?

This is the error log I found.
[*]ERROR 2010-07-12 15:59:02,160 11570399ms Object a - An error occurred during the checkout process. The checkout has failed 3 times and will NOT BE attempted again. UserId: 13093150 / 9badc2b5-f192-471c-bc50-7aa81289b0c5 Customer: / /
System.Data.SqlClient.SqlException: String or binary data would be truncated.
The statement has been terminated.
at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection)
at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection)
at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj)
at System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj)
at System.Data.SqlClient.SqlDataReader.ConsumeMetaData()
at System.Data.SqlClient.SqlDataReader.get_MetaData()
at System.Data.SqlClient.SqlCommand.FinishExecuteReader(SqlDataReader ds, RunBehavior runBehavior, String resetOptionsString)
at System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async)
at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, DbAsyncResult result)
at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method)
at System.Data.SqlClient.SqlCommand.ExecuteScalar()
at CommerceBuilder.Data.Database.ExecuteScalar(DbCommand command)
at CommerceBuilder.Orders.OrderShipment.Save()
at CommerceBuilder.Orders.a.c(Basket A_0, Order A_1, Dictionary`2 A_2)
at CommerceBuilder.Orders.Basket.Checkout(CheckoutRequest checkoutRequest, Boolean validate, Boolean triggerEvents)[/*]

Have a look at following thread
viewtopic.php?f=42&t=11207