You don't have enough usable quantity

[RonnyKing]

Hi,

 

When I try to delete a quantity of a specific product I receive the message:

 

You don't have enough usable quantity. Cannot remove 1 items out of 0

 

I have 10 pieces left of this product, so this isn't the problem. I just cannot get the quantity below 10. I only get this message with a couple of products, it is not a problem to lower the other product manualy. 

 

I use advanced stock management.

 

I have removed the stock directly in the database using phpmyadmin but I don't want to do this every time for my client. 

 

I assume this is a bug in prestashop? Does anyone has a solution for this? Updating prestashop to 1.6.1.7 didn't fix the problem. 

 

Many thanks.