City Money and ending contracts early

[Unregistered]

I have 4 city money notes left, and wanted to complete a contract early, i started a long contract with a high coin gain from it, in the hope i could use my remaining 4 notes to end the contract early and gain some coins to build more things in empty spaces in my city.

I keep getting "OH DARN! You don't have enough City Cash" yet i have 4 notes and it only costs 4 notes

Any help on this?