As Gerard said, fixed costs don't roll up to the summary level. But they DO
accumulate into the Total Cost column, added to the resource costs, and they
do roll up there. The reason they don't roll up to the summary is that it
is entirely possible to have a fixed cost that applies to an entire phase of
the project that would be entered into the summary line and also additional
fixed costs for some of the individual subtasks tasks that indented under
that phase summary. The Fixed Cost column is where those costs would be
entered, the Total Cost column is where they accumulate along with the
resource costs and roll up through the various levels.
You can verify this by a little test project of a couple of regular tasks X
and Y plus a summary task called Sum with subtasks A, B, C, and D. Go to
the view options page (Tools, Options, View) and turn on the Project Summary
Task (lower right) to get a total project level rollup. Switch to the Cost
table and put $5 as fixed cost in each of the performance tasks and $10 in
the Sum task. While the Fixed Cost column won't be rolling up, you'll see
the $5 is carried over into the Total Cost column for each of the
performance tasks. For the summary task, Total Cost will be $30, 4x$5 for
the subtasks plus $10 for the summary itself. The Project Summary task at
the very top will show a total cost of $40, the sum of the individual
performance tasks plus the summary task.
HTH
