Trick to drill down to another report?

I can't seem to figure out the trick to make one report drill down to another report.
The docs have a screen shot on page 40 that shows a report in the list, but in my case my choices are always limited to only:
Form
Do not allow drill-down to form
Form (floating layout)
Form (column layout)
I tried defining Dynamic relations between the table/views involved but that didn't do it.
What do I need to do?
Thanks
Bob
The docs have a screen shot on page 40 that shows a report in the list, but in my case my choices are always limited to only:
Form
Do not allow drill-down to form
Form (floating layout)
Form (column layout)
I tried defining Dynamic relations between the table/views involved but that didn't do it.
What do I need to do?
Thanks
Bob