Don't wait until late in the day to take money out. I tried another ATM at Banco Patagonia, across from where I had lunch, and it just rejected it when I wanted 1200 pesos.

So, at about 4:30pm, I hit the same Citibank on Florida, and each ATM gave me an error. I wasn't sure if the ATM system was down, but tried the last ATM, just in case, and got out my 1240 pesos. I guess the other two machines were out of money already! I've heard of problems on weekends, but not weekdays.