Item text inconsistency for multiple item text in CRM Billling document

Question

Hi Experts,
I am facing problem in adding item text in CRM Billiing document in Web UI.There are 3 line items in my billing document and their item text gets determined from Billing due list items but there is a requirement to change the item text at billling documnet level also to populate it in the invoice.Here comes the problem when I change item text of first item system alllows me to change in text type Sales Text but when I am doing the same with suceeeding items it throws me a exception like this.
Business Server Page (BSP) error
What happened?
Calling the BSP page was terminated due to an error.
SAP Note
The following error text was processed in the system:
Entry parameter ES_KEY of method CL_CRM_GENIL_CONTAINER_OBJECT->GET_KEY contains value , which is not allowed
Exception Class CX_SY_IMPORT_MISMATCH_ERROR
Error Name CONNE_IMPORT_WRONG_OBJECT_TYPE
Program CL_CRM_GENIL_CONT_SIMPLE_OBJ==CP
Include CL_CRM_GENIL_CONT_SIMPLE_OBJ==CM007
ABAP Class CL_CRM_GENIL_CONT_SIMPLE_OBJ
Method IF_GENIL_CONT_SIMPLE_OBJECT~GET_KEY
Line 18 
Long text During IMPORT it was ascertained that the object in the dataset has a different object type to the target object, or the structure of the complex object is not compatible with the structure of the target object. The target object has either a different length, a different number of decimal places or a different data type to the object that is to be imported.
Error type: Exception
Your SAP Business Server Pages Team
This change in item text only works for first item and gives exception for all below items,Is this a standard SAP functionality or what can be done as same thing can be done from back end.

Answer 1

Hi,
The above given thread is the perfect solution for your requirement.
Defaulting some data in the text field means, either you can use the the Substitution / BTE.
Using the substitution, system not allows you to change the text field in case of any modification you want. But with the BTE you can specify only at the time of the document posting.
BTE is the best option in this case.
VVR