Purchase Credit Memo G/L Problem

I have an issue about Purchase Credit Memo G/L. In usual, when create purchase credit memo, NAV will create a journal like below:

Direct Cost (D)

Inventory (C)

Payable (D)

Purchase (C)

But i found 1 transaction when nav create different journal in purchase credit memo:

Direct Cost (D)

Inventory (C)

Payable (D)

Purchase (C)

Inventory (D)

Direct Cost (C)

That journal make an outstanding amount in Direct Cost and Inventory. When i check to Value Entries, i found that 2 additional journal create for cost adjustment. But i have no idea why adjust cost can create these journal. Anyone can help? This is bug or what? Thanks…

Which NAV Version is this issue you are facing ?

How have you created this credit memo (i.e Copy Document functionality, manually creation & application before posting).

This issue is used in NAV 4 and I use manual creation to make this Credit Memo. But this issue is happen in this one document only.

Thanks…

And what about the application ?