proper syntax for distinct count

[#1]

I need to do a distinct count of Rx# when Refill# = 0. Here's my expression so far...

Count({$<[RX#]=P({1<[Refill#]={0}>}[RX#])>}[RX#])

How do you tweak this to include a distinct count of RX#?

I'm failing at figuring this one out.

Thank you.

[vinafidalgo]

Try this:

Count(Distinct {$<[Refil#]={0}>}[RX#])

[Clever_Anjos]

DISTINCT clause must precede you Set Analysis expression

[#4]

Thank you Vinivius!