set analysis with aggr()

[stepguti]

I need to get a distinct count for sum billed of all claims where billed > $1000.  Can someone help me write this syntax.  I'm guessing I'll start with something like this 

Count(Aggr(Sum(BilledAmount), ClaimID))

but not sure how to incorporate set analysis to only get the distinct claim count where sum billed amount >$1000.

Thanks in advance! 

[Channa]

Count(IF(Aggr(Sum(BilledAmount), ClaimID)>100,ClaimID)

[pradosh_thakur]

Count(Distinct {<ClaimID={"=Sum(BilledAmount)>1000"}>} ClaimID)