If you have been faced from time to time with a whacky ‘PrinterCal’ graph when reading in a printed profile target, it most likely means there are bad readings in there. 

Here’s an example of some bad readings in an end graph result:

So whats the easiest way to find out where it went wrong?

1. In PrinterCal go to Measurements Menu > Show Measurements
   
2. Go through each page in the measurements and check the colours of the inside of the chip (measured colour) versus the outside of the chip (target colour). 
3. To swap pages click the down arrow at the top left of the window. 
   
4. Once you find the mistake you will need to re-read this line and/or chip.
   
   The image below shows that most of the chips look similar on the inside and out, however the middle line has huge colour differences between the target and actual reading. This is how we tell it is wrong.
   
   
5. To re-read this line click on the chip furthest to the left
   
6. Go to Measurements Menu > Start Measuring. This will take you through the process of re-calibrating your device, you can then re-read this line. 
7. Repeat the above steps for any other mistakes.