In order to understand how the data recorded in the tables are, you should show an example with the same, because it is not clear whether DiscountAmount and ItemDiscount are two discounted amounts or are percentage values which will allow the relative amount to be discounted.
If logarithms must be base 10, divide the expression by Log(10)
495 / (1.29579 - 0.35004 * (Log(87 + 97 - 32)/Log(10)) + 0.221 * (Log(167)/Log(10))) - 450
which as a result of 33.7396011841917
If the relationship between Trip and Vehicles is correct the query is correct, perhaps if you attach the file it is easier to show you how you should change for what Pat Hartman rightly said.
Try modifying the query by entering DISTINCT.
SELECT DISTINCT StockID, StockNo, OnOrderQty, Allocation, allocated, batchno
FROM StockLevels
WHERE StockNo=[Forms]![stocklevels]![Stocklist For Purchasing].[Form]![StockNumber];
Meanwhile, you can try to simulate the import by working with all the files on your computer.
If everything is correct in this case the problem is with the server.
However, if you provide the sample files we could also check what happens.
I think there are problems in the structure of the tables involved in the orders as, in my opinion, the structure should be:
tblOrders
OrderID
OrderNumber
OrderDate
SupplierID
etc...
tblOrderDetails
OrderDetailID
MaterialID
MaterialQuantity...
In the attachment you will find an example.
However, the first thing to do is learn how to manage the properties of the various fields of the tables and in particular:
Size (if the type is Text, don't always leave 255 set as you almost always won't need all those fonts (this is to avoid...
You say 100m and 300m combination is allowed but the 300m event is not in the event list (100M, 200M, 400M, 800M, 1500M, 3000M, Long Jump, High Jump, Shot Put (5.00Kg) , Thread (1.5Kg), Javelin (700 gms), 4x100M & 4x400M Relays)