Having a bit of an issue , trying to print barcode lables for inventory Items , but I cannot find the correct form that it is expecting

View

Inventory

Print labels

Inventory

I have selected the option to print the Item code as Barcode , however I cannot find the correct layout that it wants, I have tried (I think) all the label type forms , but they all give me the same reply on the screen

 "The file you selected has and invalid format for the report requested":

and the OK button is greyed out.

Please can you point me in the right direction with some instruction  , and where the label forms are stored? I am obviously missing something.