average plane of 3D plot

[#1]

I am trying to find an average plane of a surface.

my data include X, Y, Z.

I run analyze->fit model->Y variable=Z, Model effects=X,Y.

then i choose factor profiling-> surface profiler to see the plot+ average plane.

this is my plot when i run scatterplot 3D:

and this is my plot when i run fit model:

there is some transformation that change my data from dome to cylinder.

 any idea what to do?

[#2]

I'm not sure what the green plane means, but the video might help. Drag the Z-axis to expose more data.

[#3]

i can't see the video

[#4 · Accepted solution]

Sorry, don't know why that is. It would show dragging the axis like this:

Use the mouse; the cursor changes to a hand over the axis.