Help - barcodes in invoices

Is anyone able to help me please?

I am creating invoices for product sales, and am wanting to streamline the process - I have created the item codes the same as the barcodes, and am trying to scan the barcode into the item number however it is not recognising the item number and is just popping up with a create new item code. I know it's not the scanner as the barcode is scanning the correct code in the description box, and I have tried to create a new item from the barcode scanner pop up box but it when I test the same barcode on a second line i'm back to square one.

Please tell me there is a way to make this easier for me!!