pivot table jocks?
 

Alright, I am pretty good with pivots, but I cannot
figure out what seems like the simplest thing...

Basic problem is that the total function for one of the
groupings is not giving me an average, despite the fact
that I definitely indicate that to be the summary
function desired. It just gives me a blank in the total
lines.

Basic info:

Fields - End Page (number), Start Page (number), Date,
Start time (time format), End Time (time format)

Formula for data field is "(End Page - Start Page + 1)/
((End Time - Start Time) * 24).

The table groups by person, then task (what activity they
did), then date, with the data area having the field
defined by the formula above. Each individual data point
is calculating the pages/hr (which is what the formula
represents) correctly. The summary line (which is set to
summarize with 'average' function, however, is not
getting me anything other than blank. When it is set to
automatic, it does give me something, but I don't even
know what it's calcuating (not the sum, and not really
any combination I can come up with).

Another point...some of the tasks (which group as the
second level) do not have pages associated with them, but
all have times. So I figured this would not cause error,
since the problem would be if the denominator (which is
based on time) were to be zero (DIV#0 error)

Any insight someone can share?