It seems you are using the barcode scanner as a HID device (similar to typing)
Clicking in the Program window and then scanning the barcode can lead to this kind of mixup on some machines.
Try clicking on the Select button (shown in attachment) and then scanning it in the file selection window.
It should work in all likfelihood.
If you have regular use of barcodes, then get the barcode module activated through Homag.
You will also need to buy a COM-enabled barcode scanner.
After this, the result will be seamless with no clicking / accepting.
Simply scan the panel and start machining.
No need to goto the computer.