net value and tax is not apperaring properly

dear all,

Scenario : Direct Sale to customer (MTS) from Factory

In this specific pricing procedure we take PR00 value as assessable value .On this we add BED and ECESS excise duty and arrive at Sub Total . ( PR00BEDECESS)

We mean this value as Net Value

This value should be picked in field (VBAK - NETWR) of a sales order .But now system is picking PR00 value.

Similarly, instead of picking tax amount of ( CST/VAT) in tax field (MWSBP) , now its picking tax and duty(BEDECESSCST/VAT) which is not correct.

Kindly suggest as to pick right values as we desire above. Is there any note supporing as to how to achieve the same.

Pls suggest

Thanks in advance......

Shankar