DSum Not Coming Up With Correct Total

I have an Inventory DB Table called [EngData] that has a subform table called [Inventory]. I have in the subform a calculated text box that Sums three columns, StockQtyMade, StockQtySold and StockQtyShrink. This works perfectly.

On the Main form I have a calculated text box that references the subform calculated field. This also displays correct info.

On another Form I wanted other users to see the total stock on hand by using a calculated field called PullTotalQty. This is set by using DSum(...). The only problem is that the DSum(...) keeps giving totals that are not accurate. Sometimes the quantity is a few pieces less then the correct amount and in other cases the qty is many times what it should be.

Whatever the amount in error it is consistent each time a particular record is displayed. I have tried many things to get this to work but nothing has fixed the issue. I have also tried changing the query and nothing works. Changing the query and using the [Inventory] table in the DSum domain gives a different wrong quantity.

Here is the code: I reduced the code down to one column to be summed (StockQtyMade) just to see if I could get that working first. I will add the other two columns later. for testing purposes I am only looking at the StockQtyMade amounts.

Me.PullTotalQty.Value = DSum("[tblInventory subform].[Form].[StockQtyMade]", "[SumStockQuery]", "[tblInventory subform].[Form].[PartID]= " & Me.[ID])

Here is the SumStockQuery SQL:

SELECT Inventory.TransactionID, Inventory.PartID, Inventory.PrintNo, Inventory.StockRev, Inventory.StockQtySold, Inventory.StockQtyMade, Inventory.StockQtyShrink, Inventory.StockQtyXIncomplete, Inventory.StockLoc, Inventory.TransactionDescription
FROM Inventory
WHERE (((Inventory.TransactionDescription)<>"xNextOP"))
ORDER BY Inventory.TransactionID DESC;

Why the totals are incorrect??