Help with Max(date) per keyField - get most recent data

[Scott Critchley]

I have a large list of daily stats from various systems, i.e.

Table Stats
SystemID | tagID | dtStamp | Value
S001 : T100 : 2006-03-23 : 50
S001 : T101 : 2006-03-23 : 2
S001 : T100 : 2006-03-24 : 53
S001 : T101 : 2006-03-24 : 5
S001 : T100 : 2006-03-25 : 60
S001 : T101 : 2006-03-25 : 8
S001 : T100 : 2006-03-26 : 65
S001 : T101 : 2006-03-26 : 12
S002 : T100 : 2006-03-23 : 10
S002 : T101 : 2006-03-23 : 1
S002 : T100 : 2006-03-24 : 12
S002 : T101 : 2006-03-24 : 2

I need the date of the last record of data for each site for each tag. (i.e. the most recent data for each site)

I tried using max(dtStamp), but it found the biggest date in the table and tied it to every system/tag the same. i.e. it showed 2006-03-26 for S002/T101, even though I know I don't have data for that site on that day.

Thanks!
Cheers,
Scott.