Scan parts OUT to Sheet1, parts IN to Sheet2 and list in Sheet3

[Nu2Java]

Hello,

(Workbook attached) I have this simple useform to scan barcodes of parts to check if they match or not, if they do, it will log them to Sheet1 when scanning parts "OUT" of stock. What I will do is have the same code for Sheet2 for scanning parts "IN" to stock. What I want to be able to do is run a macro that will populate Sheet3 for the parts that did not come back to stock. So, they were checked "OUT" but not "IN".

Can someone help me with this? Thanks for your time and help... greatly appreciated!