Minimum of a Distinct count

HI team,

I have the following Distinct count in GF 6:

DistinctCount ({ServiceHistoryWeightAudit.ServiceHistoryUID}, {@dow})

I now want to show the MINIMUM in GF5

I tried this:

Whileprintingrecords;

numbervar MIN;

  MIN := Minimum (DistinctCount ({ServiceHistoryWeightAudit.ServiceHistoryUID}, {@dow}))

but Cyrstal says that the distinct count cannot be summarized.

Thanks on your help for what I should use.

Sabine