why do i get a straight line transit fit?

[gboyle]

my data suggests a decent curve but for some reason the model plot is a straight line..
anything obviously wrong?
thanks
gavin

[karenacollins]

Answered here:

http://astroimagej.1065399.n5.nabble.com/why-do-i-get-a-straight-line-transit-fit-td1120.html