Cannot create AttachedFile for InboundDelivery with ABSL

Hi, experts.

       What I want to do is to transfer the attach files from my custom BO to InboundDelivery.

       I have created a custom BO with a BO action. I also have an AttachmentFolder node"ItemAttachement".

       In the BO action, I have written these codes.

instInboundDelivery = InboundDelivery.Create(elInboundDelivery_Root);

if(this.ItemAttachment.Document.Count()>0){

    dTypeCode=this.ItemAttachment.Document.GetFirst().TypeCode;

    dName=this.ItemAttachment.Document.GetFirst().Name;

    dAltName=this.ItemAttachment.Document.GetFirst().AlternativeName;

    docDescription=this.ItemAttachment.Document.GetFirst().Description;

    docBinaryObject.content=this.ItemAttachment.Document.GetFirst().FileContent.BinaryObject.content;

    docBinaryObject.mimeCode=this.ItemAttachment.Document.GetFirst().FileContent.BinaryObject.mimeCode;

    if(instInboundDelivery.AttachmentFolder.IsSet()){

     instInboundDelivery.AttachmentFolder.CreateFile(dTypeCode,dName,dAltName,docDescription,docBinaryObject);

       }else{

     var attFileInstance=instInboundDelivery.AttachmentFolder.Create();

      instInboundDelivery.AttachmentFolder.CreateFile(dTypeCode,dName,dAltName,docDescription,docBinaryObject);

    }

   }

But it is not working. The attach files cannot be saved in InboundDelivery.

Regards,

Fred.