If there are extra spaces or special characters in the invoice number,it creates junk in BUSY,to resolve this you can follow given steps:
Step 1:Go to the Administration menu,
Step 2:Click on Configuration,
Step 3:Click voucher series configuration,
Step 4:Click on sales and select series,
Step 5:Click voucher numbering,here you can check is there is showing any extra space, then you need to remove it,and set numbering accordinglly.
Step 6:If you maintain voucher numbering manually,you will need to check the voucher to see if there are any extra spaces or special characters you need to remove it then it will be resolve.