I ran a harmonic response to a force acting on the panel, simply supported at the edge and with the two nubs in the back allowing it free z movement (as shown in the picture).

Any idea why the Total Deformation is different (or less than) from the Y-Axis deformation? 
And why the amplitude in the Y-direction is different between the Y Deformation and the Y Axis Frequency Response?

I'm kind of new to this, so I apologize in advance if I'm overlooking something obvious or something.
Larger Pictures!