Characteristic in MCSI not Updated for Invoice Items

Hi.

I've built an info structure, which gets data from invoice items. However, there's a specific characteristic in this structure that only gets updated for the first invoice item.

Could anyone give me a hint of how to investigate this? I've been working in SD for over a decade, but never before in statistics (strange as this may seem...), so I really don't know where to start.

Help will be greatly appreciated.

Cheers.

Nuno Ferreira