How to check split valuation change log

Hi All.

Issue is when user is going to change the material in related field  valuation category that is 'S' to 'V', system is throwing error "valuation category for the plant  S missing".

My analysis is , I checked for the  plant  how many materials are with valuation category S, I found more materials with S and same passed into purchase order history, I found document also.

Why user is changing the material with S to V is, while doing goods receipt with respect to PO system throwing error because of valuation category.

I  think recently activation for the valuation category "S" got deactivated in split valuation configuration.

My question is.

1) How to  check the change log who has made the deactivation in split valuation configuration.

2) What is the impact if we activate now.

Please help me.

Thanks

Mahesh