Hi Jose,
From the schedule lines its very clear that how many quantities and date on which you can do the delivery.
So from your first screen shot. you will be able to deliver only the remaining quantity of delivery date 5.12.14 + the tolerance ( 17500 - 380 + tolerance). Dont go for the tolerance quantity. but do deliver only the remaining quantity., then there is no confusion.
This is a standard and proper system behavior.
Thanks
Jobi