Negative value in maintenance orders - only work hours

Hello,

I have a maintenance order that show me a negative cost. In this maintenance order I have only work hours , I not have materials.

But when I opened  a report costs, I can´t get this value..

I tryed too see this maintenance order in transaction kob1 (without filters criteria), But I can´t again get the value -1706,61.

How As I can understand the calcule that SAP did to show this negative value? Have another report to this?

This maintenance order is already settled costs.

Thanks in advance