Can't Access Extension Fields

Hello everyone,

I'm trying to do a mass upload of data to selected fields via XML. These fields are extension fields created using adaption mode in the customer's ByDesign system. I found the following tutorial, and decided to use the theory behind it.

http://scn.sap.com/community/business-bydesign/blog/2012/05/27/epic-tutorial--mass-load-extension-data-to-a-bydesign-business-object-post-implementation

Because the object I'm using --- CustomerContract, to be precise --- is not a flat structure (each contract can have multiple items in it, and each item has the same two extension fields in), I adapted the code from the above link, such that I have:

The custom BO to 'load' the data fields, as suggested above:

And the ABSL AfterModify file for the Root node:

The two extension fields --- RecoveryPercentage and OverheadAdminPercentage --- have been referred to in a .ref file, which has been activated. Neither field is marked as display only in the properties list in edit screen mode in the ByD system, and yet the SDK throws an error when trying to set their values.

Anyone got any ideas why this is the case?

Cheers,

Lewis