Foreign Tax Credit Schedule 3 Line 1 Less than Combined 1099-DIV Box 7

I am using TT Deluxe desktop.

I have entered two 1099-DIVs with amounts in Box 7 that total $163.85.

I have gone through the Foreign tax questions and allocated the dividends to appropriate countires.

However, Schedule 3, Line 1 Foreign Tax Credit Worksheet shows only $144 and that is the figure that flows through to the 1040, Line 21. As a result, I am not getting full credit for the foreign tax withheld. 

I qualify for the exemption from using form 1116 as the amount is under $600. Foreign income is all dividends from RIC or Taiwan. An explanation for the $20 difference would be appreciated.