In Manage Import Map, If the item class is blank, how to configure Excel to display an error?

Summary:

In the section of Manage Import Map, I would like to configure Excel to display an ERROR or WARNING if the item class is blank.

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・Navigation pass

   Home>Product Information Management>Manage Import Map>Create Import Map >Create expression >Validate

 

・Content

  In the SPREADSHEET section of the import map, I would like to configure Excel to display an ERROR or WARNING during validation if the item class is blank.

  After unhiding the sheet in Excel, I confirmed that although the item class is configured as 'Y' on sheet 2 (image 1), it is occasionally not validated in data sheet as expected (image 2).