Intermittent add to database of SKU value

My ecart was working but I needed to add the parameter SKU to the database which was previously not needed.

1. Edited the eCart server behavior and added SKU column.
2. Deleted and re-added the Add to cart buttons to add the SKU link on the Purchase page
3. Edited the Checkout server behavior Ecart get contents from ecart1
4. Edited the Confirm page to change the save orderdetails server behavior to store the value

After all this everything seemed to work and the value was now being added to the database when an order was placed.

Then I noticed it didn’t work sometimes and the value was not being stored.

Now the situation is it works after clearing the browsing history and then placing an order. However the next time an order is placed the value is not added to the database, unless I clear the browsing history first.

I do clear all session values on the success page.

Did I miss a step, do I need to edit another page?

I have included the Purchase page with the add to cart buttons because I suspect it may be the source of the issue.