The following instructions are for v7 but I don't imagine v8 is any different. From the beginning...
With all the address book records displayed that you wish to graph on:
[1.] Select Tools > Graphing
[2.] Checkmark the UDF for birthdate
[3.] Click the "Ranges..." button
[4.] Click the "Add..." button
[5.] Enter range(s) (ie: 1/1/1946 - 31/12/1955)
[6.] Select a range or ALL - click "OK"
[7.] Checkmark the range(s) under the column 'Field Values'
[8.] The ranges selected in Step 7 will show up under 'Values to be graphed for:'
[9.] Click "OK"
[10.] Select the type of graph, etc. and then click "Finish"
This works for me. Typically when the message you received is displayed either no address book records are displayed or there is no data (ie: birthdate) within the range.
If you want to save your graph settings for future use click the "Catalog" button on the resulting graph.
- IRIS