If you are using analog read pin with another Calliope mini running analog write pin, then things can get tricky. Remember that the Calliope mini that runs analog set pin writes 0’s and 1’s at a very high frequency to achieve an average of the desired value. Sadly, if you try to read that average from another Calliope mini, then the Calliope mini will either read 0 or 1023. You could try to read a higher number of values (e.g. a million) in a loop, then computer then average. Alternatively, you can plug in a capacitor in-between the two Calliope minis.