If you have both tables in your Access front-end, have you tried to create an append query using the query wizard and see if it works?
https://community.powerbi.com/t5/Des...or/td-p/310074
Can you post a couple of pics with the two tables in design view from your Access front-end?
Also, can we see your VBA sub where you are trying to run this from?
Cheers,