Sterling Commerce - Invalid quantities

If you get the next error or something alike, when submitting a toolkit:

Total Quantity of Next Lower Level Trade Item not equal to sum of Item Link Quantities back to top

Description:	Quantity entered on the Link Tab does not agree with the quantity supplied on the Global field - Total Quantity of Next Lower Level Trade Item
Steps to Rectify:	Review value entered on the Global tab for Total Quantity of Next Lower Level Trade Item. If this value is correct update the quantity for this Trade Item on the Link tab to reflect the same value. If the value originally entered on the Global tab is incorrect update accordingly and verify that the same value is supplied on the Link tab.
Item Number	GTIN	Retailer	Market	Invalid Data
	70000000000001			Total Quantity of Next Lower Level Trade Item = 12, Total Quantities from Item Link = 24

The problem most likely is because your I2 of 5 was previously registered with a different UPC child element. Search your I2 of 5 and UPC and verify if it was used before.