Query Problem (lack Of Knowledge On My Part)

Hello,

I've been trying for a couple of days now with the following problem in SQL

Ive a table called tblRresults that has the following

Date - just a regular date

OfficeLocation - just a unique id such as a zip code

SampleType - contains things like wall, floor, beam

SampleResult - "Detected" or "NotDetected"

When populated the table can look like

12/12/05   99505   Wall   Detected

12/12/05   99505   Wall   NotDetected

10/04/05   99211   Beam   Detected

10/04/05   99211   Beam   Detected

10/04/05   99111   Floor   NotDetected

10/04/05   99111   Floor    NotDetected

What I want is (I guess) a crosstab query that produces the following

Date         Location   SampleType CountDetected   CountNotDetected   

12/12/05   99505      Wall                  1                        1

10/04/05   99211      Beam                2                        0 (or null would be ok)

10/04/05   99111      Floor                0                        2

Any help gratefully accepted, this has been driving me mental!

thanks