Using Nano to burn fuses on 3v3 Pro Mini

I was hoping to use a 3v3 pro mini for a low power sensor as described here, which suggests burning some fuses.

I don't have a dedicated programmer, so I thought I would try and use my spare Nano and program it with the ArduinoISP sketch.

I think I have connected the pins correctly (double checked this morning after a night sleeping on it), but I get the following response from avrdude

C:\WinAVR-20100110\bin>avrdude -c arduino -p m168 -P com4 -n

avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.00s

avrdude: Device signature = 0x000000
avrdude: Yikes!  Invalid device signature.
         Double check connections and try again, or use -F to override
         this check.


avrdude done.  Thank you.

which I think means that the nano isn't getting anything back from the pro mini.

Having set all this up I realized that I may be optimistic in expecting the 3v3 mini to talk back to the 5V Nano. Should this work?

Is there any other reason this error can happen?