3dsurf2vol negative values?

Hi there,

I am trying to bring the results of a surface group analysis done using 3dANOVA2, back into volume space using the 3dsurf2vol command. The following command works well except that it only seems to bring over the positive values from my contrasts and not the negative values. Any idea on what I am doing wrong or if there is some way to fix this?

Here is the command I am using:
for h in $hemi
3dSurf2Vol -spec std.141.MNI_N27_$h.spec
-surf_A std.141.$h.smoothwm.gii
-surf_B std.141.$h.pial.gii
-sv MNI_N27_SurfVol.nii
-sdata surfANOVA.$h.20.allTR.block.niml.dset
-grid_parent MNI_N27_SurfVol.nii
-map_func ave
-f_p1_fr -0.2
-f_pn_fr 0.1
-prefix test.$h.nii