Count if formula needed

I have to count dates. But the condition is, the data of one field should be greater than 0.

So if Amt >0 for a date then count that date as 1 and so on.

I tried to formulate it as:

If(Amt >0) then(count(date))

But I have groups on month field and orgnization field.

How will the formula change? I addded count({date},{@month}) but it shows 31. I want 31 - number of dates in which amt <=0

Thanks