Ok, I also made a mistake.
To calculate the amount of Foreign Tax Carryover for form 1116:
Total Foreign Tax Paid (Line 9) - Maximum amount (i.e. limit) of credit (Line 21)
Look at IRS publication 514 Carryback and Carryover. You must keep a running calculation of prior years and publication 514 has a couple good examples.
Another good example is here:
https://www.greenbacktaxservices.com/blog/foreign-tax-credit-carryover/
