This error message means that the Tax Rate on the order can't be matched up with any of the Tax Rates that exist in Quickbooks. You can find out which rate didn't match up by appending /admin to the app URL
Here we have all kinds of useful data including the Internal Message.
In this case, the rates Broward County Sales Tax and Palm Beach County Sales Tax have the same agency and rate, and there was nothing in the name that could help us pick which one to use.
To solve this the merchant can use different tax agencies or name the tax according to the location. If a merchant has really complicated and non-conventional tax setup the app may fail to find a tax rate.