Positive value in credit memo request

Hi Experts,

We are creating credit memo request from sales order reference. We are using different pricing procedures for both.

In VTAA, pricing type used as X. ( no idea how it works).

Condition type YVKD is used in both pricing procedures but base calculation type used in original order but nothing in the credit memo. ( net value calculated based on this condition)

Some of the document condition type determining as positive value . Why?. ( price value is getting copied from original order).

Anyone can help.

Regards,

Raja