Hi Hawazin,
If the formula uses Summary functions or Print Time functions, you cannot use the 'Insert Summary' option to create an Average.
You'd need a manual calculation formula that looks something like this:
EvaluateAfter({@Formula you need to average})
shared numbervar avg;
shared numbervar cnt := cnt + 1;
avg := avg + {@Formula you need to average};
Place this on the same section as the other formula.
Next, create a formula to display the average and place this on the footer:
shared numbervar avg;
shared numbervar cnt;
avg/cnt;
-Abhilash