Ok I've done the queries and managed to get a single query with the 3 results I want by first putting these 3 select statements as individual queries:
SELECT Count(*) AS Age1
FROM tblMemReg
WHERE ((Round(DateDiff("d",[DOB],Now())/365.25))<16);
SELECT Count(*) AS Age2
FROM tblMemReg
WHERE ((Round(DateDiff("d",[DOB],Now())/365.25)>15) And (Round(DateDiff("d",[DOB],Now())/365.25)<18));
SELECT Count(*) AS Age3
FROM tblMemReg
WHERE ((Round(DateDiff("d",[DOB],Now())/365.25))>17);
Then merging them into one query:
SELECT qryAge1.Age1, qryAge2.Age2, qryAge3.Age3
FROM qryAge1, qryAge2, qryAge3;
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This outputs:
Age1 | Age2 | Age3
.....3 .......2 ........7
(And I have 12 rows in the tblMemReg table)
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Now if I use the chart wizard and get it to use the last merged-results query, it doesn't work.