Error in formula

Hi All,

I get the "A String is required here" error with my formula and it higlights the line in bold.

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

Thanks in advanceYour third line will return an integer - all statements must return the same type. Wrap the third line in ToText().