Effective price is &1 &2, material price is &3 &4

What causes this issue?

INCLUDE NA_MATPRICE Language EN
The system has checked the <LS>tolerances for price variances</>
defined in Customizing, and has already informed you of this variance
in a system message.
<ZH>Effective price</>
To be able to compare the effective price determined in the purchase
order with the material price in the material master, the effective
price &V1& &V2& is converted into the base unit of measure and price
unit of measure stored in the material master.
<ZH>Material price</>
The material price &V3& &V4& refers to:
The current price (for example, standard price, moving average price)
in the material master, and
The price unit in the material master
<ZH>Note</>
If the purchase order contains a different currency, the effective
price is converted into the local currency.

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Example 1
A material costs $10 per piece (pc) in the purchase order.
A material price of $5 per 10 pc is stored in the material master.
Because the price in the material master is given per 10 pc, the
effective price is also calculated for 10 pc.
The price in the purchase order is first converted into the base unit
of measure for the material in the material master, then into the price
unit in the material master.
The effective price for 10 pc is therefore:
$10/10 pc * (no conversion into base unit) * 10 pc = <ZH>$10</>
<LS>The effective price is $10, the material price is $5 (per 10 pc).
</>
Example 2
A material costs $10 per carton in the purchase order (1 carton = 10
pc).
A material price of $4.50 per 5 pc is stored in the material master.
Because the price is given for 5 pc in the material master, the
effective price is calculated for 5 pc.
The price in the purchase order is first converted into the base unit
of measure for the material in the material master, then into the price
unit in the material master.
The effective price per 5 pc is therefore:
$10/1 Carton * 1 Carton/10 pc * 5 pc = <ZH>$5</>
<LS>The effective price is $5, the material price is $4.50 (per 5 pc).
</>

How to fix this error?

INCLUDE NA_T160M LANGUAGE EN
Display the conditions for the item to determine how the effective
price has been calculated by the system.

Error message extract from SAP system. Copyright SAP SE.