Help with Formula

Hi Karl

Let me explain a little

I have fields SS0 to SS21 with dropdown to select 0, 1, 2, 3, 4

This is what I want

There are 22 criteria and each criterion can have a maximum point of 4 points, therefore, 22 X 4 = 88
Maximum points may vary depending on the total number of criteria addressed during the evaluation. If criteria is not evaluated, enter “N/A” and these will be deducted from the maximum points.
To compute the student’s grade:
Total points received (excluding N/A) / Maximum points possible 88 X 100 = % grade
Example: Student received 80 points (had 2 N/A) / 88 X 100 = 90.9%

This is what I currently have. I keep getting zero. Your help is appreciated.

var nCount = 0;

var nSum = 0;

var na = 0;

event.value = 0;

for( var i=1; i<=6; i++){

if(this.getField("SS0"+i).valueAsString == "N/A"){

na++;

if(na == 6)

event.value = "N/A";}

else if(this.getField("SS0"+i).valueAsString != "N/A" && this.getField("SS0"+i).valueAsString != "" && this.getField("SS0"+i).valueAsString != 0){

nCount++;

nSum += Number(this.getField("SS0"+i).value);

event.value = nSum/nCount;}}