Net price for item & taken from conditions

What causes this issue?

You have entered a net price. However, a
<DS:GLOS.3526BFD2AFAB52B9E10000009B38F974>purchasing info record</>
relating to the material to be ordered already exists.

System Response

The net price will be taken from the info record.

How to fix this error?

INCLUDE NA_T160M LANGUAGE EN
If you want to enter a different price, you must maintain the price
with the conditions of the item.

Error message extract from SAP system. Copyright SAP SE.