Averages with decimalised values

I am trying to work out the average grade based on our crude levels system whereby they are decimalised to a .2 or a .5 or a .8 (indicating confidence within a level boundary). Whenever I try to average this, I get an N as my outcome. Is this usual?

Nope, that's unusual, to say the least! I'm not familiar with N as a result

You should check the grade type you are assigning to that average column -double tap on header > Grade type - and you should also make sure that there is a grade type assigned to the rest of columns.
When configuring the calculation, once you have the arrows on screen, you will see the grade type below each column.
If still can't sort it out, do let me know

Sorted. Thanks!!