Unable to cancel sales order line. Got an error.

Summary:

User created sales order. That has 2 lines (1-1 and 1-2). 1-1 is closed and user wants to cancel 1-2 but she the below error, "Order Management can't price the sales order because it can't identify a charge for item ****, with unit of measure MT"

User wants to know why she needs to update the prices if at all she has to cancel the line?

Content (please ensure you mask any confidential information):

Version (include the version you are using, if applicable):

Code Snippet (add any code snippets that support your topic, if applicable):