Update Pricing in VF02

I followed these 5 steps

1. Enter billing Doc in VF02

2. Select an Item

3. Click Item Pricing Condition

4. Click Update button

5. Choose Carry out new pricing

After this, I found some of the condition types missing in the billing document. where Can I find the code for this deletion of records. I went thro debugging but its taking lot of time as standard program is involved.

Please suggest a way forward.

Thanks

Tharani