Help with crosstab

I need to create a crosstab report. I have never done it before and need some help with it. I would appreciate any help and guidance.

I have a report that has the grouping as below

Region
Sector
Interval
Area
Crew

I need to add a crosstab report in the interval group header that will summarize the data by area and crew. I go to Insert crosstab and select Area as my column heading and Crew as my rows. Then I want to use @.PercentComplete formula as the summarized field but I don't see it in available fields and even if I create new formula from within the crosstab window I still don't see it. Any suggestions as to why I am not seeing this formula. Formula is as below

If {@.ScheduledTasks} = 0 then
"N/S"
Else If {@.TotalTasks} = 0 then
"N/D"
Else
cStr( (sum({@.TimelyCOmplete},{@.Group_CrewUnit})/(sum({@.TimelyCOmplete},{@.Group_CrewUnit}) + sum({@.MissedTasks},{@.Group_CrewUnit}) + sum({@.LateComplete},{@.Group_CrewUnit}))) * 100, 2)

Sample data for Crosstab is below

Crew Area1 Area2 Area3 %Complete
AAA 100 100 N/S 97.61
BBB 100 N/S N/S 100.00
CCC 0.00 100 N/S 81.25
DDD N/S 100 N/S 100
EEE N/S 96.87 N/D N/D
-- --- ---
%Complete 98.28 100.00 N/Danyone?