Sounds like memory failed me on that old thread.
Without actually testing it, I believe the analog channels are 0 through 3, which might be why "4" has an issue. The pin numbers below are the DIP pin numbers:
ADC0 Pin1 PB5 (RESET)
ADC1 Pin7 PB2
ADC2 Pin3 PB4
ADC3 Pin2 PB3