Asset accounting Data migration

Dear Friends,

I have some functional doubts as i mentioned in screen shot

Net book value must be Acquisition value- Acc  Depreciation= Net book value

But in my case when i'm doing AS91 system is showing as i shown i screen shot

                                                                                                           Net Book value= Acquisition value+ Acc Depreciation

Can you please give me the suggestion is how can i get correct net book value.

Thanks & Regards,

Sreehari.