if you receive the following error:
This key is already associated with an element of this collection
Check your import file to see if there are extra spaces between the name that is being added (Customer, Vendor, Item, etc). The issue is most likely that you have something like the scenerio below:
Customer Name being added
RIGHT WAY CLEANERS (note the extra space between the first and second word)
Customer already exists in QuickBooks as
RIGHT WAY CLEANERS
When TPI goes to look for the customer in QB it doesn't find it (with the extra spaces) so TPI then tries to add it. The problem occurs because QB strips the extra spaces when we go to add the customer. This behavior within the QBSDK causes the problem.
Remove the extra spaces from your import file and retry the import.
Also try adding the customer/vendor etc manually into QuickBooks and see if an error results.
If you are importing data that includes employee name make sure the format in the import file matches the employee list in QuickBooks. For instance Mary Jones is not the same as Jones, Mary.