Foreign Tax Credit Carryover

Last year I reported a sale of land in Canada.  On that sale I paid $7,308 (in US$) to the Canadian government and filed for FTC.  The calculation on my Turbotax return allowed me a credit of $3,589, with the balance - I assumed - to be carried over to this year's return.  This year I have no foreign income but when I enter a carryover amount of $3,719 ($7,308 - $3,589) TT makes no changes to the amount of my refunds.

 

Am I doing something wrong, or is there something I don't understand?