Congruent Parallelograms?

Although you may not be able to tell by the picture, these blue and yellow parallelograms are the tops of two led containers for my mechanical pencil. I traced them with help from the construct>parallel line, construct>perpendicular line, and construct>midpoint tools in The Geometer's Sketchpad.
I drew two altitudes (k and n) in order to find the height of each parallelogram. Then, I multiplied each height by its corresponding base and, to my surprise, found these parallelograms to not have equal areas, and therefore not be congruent.
The total area of parallelogram ACDF is 17.16 square centimeters.
(~GC2)