Our company has the feature on QB set to NOT allow negative inventory...It is in place as a safeguard so we don't accidently bill out an item that a customer did not receive. 

With this feature on;  we cannot simply delete an item receipt and reenter if the customer has already been invoiced as it then takes it to negative inventory; QB won't allow us to delete the item receipt.  

We have to manually alter inventory to get the invoice entered. It is a hassle definitely;