Crystal Report Count in a Formula Field

[denny1824]

I have a crystal report that someone else wrote and already has a Formula Field

if Criteria then (Count ({FirstField},{SecondField}) / Count ({FirstField}))

When the Criteria is true, this calculates a percentage for all rows. This Formula Field is then used as data in a bar chart that uses FirstField for the x-axis and the percentage for the y-axis. That was all already working just fine.

Now I need to change it so that the Count will only count if a third field is not null for that row (something like: if not IsNull({ThirdField}) ).

I added "and not IsNull({ThirdField}) " to the Criteria. That makes it so when ThirdField is null the Formula Field is zero(which I want), but when the ThirdField is not null, it calculates the percentage for all rows, including the rows where ThirdField was null.

I need someway for it to only do the count of Rows that the ThirdField is not null.

Yes, I am new and I dont even know what the comma is doing in the count(x,y) command.

Thanks in advance