Sometimes once adding a sale of nursery or finishing it might appear a message informing that the operation will result in a negative balance, even though you see number of piglets in the group on the screen.
That can occur because the system will check the amount you have to sell from the data entry date, so if you are adding a sale from a sale that happened last week, the system will check if you had that amount of piglets on this date of last week.
For instance, lets look at the group 10, this group has 80 entries between the Sep. 25th and 26th, and later on Oct 04th another entry of 20 piglets.
However, if you try to add a sale of total amount of 100 piglets on the date of Oct. 10th you will be seen the following message:
That is because on this date you only have 80 piglets on this group, therefore the system will not let you sell more than 80 piglets on this date, even though the system shows you that you have 100 piglets in this group. So you will only be able to sell 100 piglets in the same data entry if the sale is dated after Oct 4th.
So every time this message shows on your screen, check the entry date of the animals and the sale dates to make sure that you are selling the amount of animals available on the sale date.