Hi, FreeSurfer experts

I noticed that when I automatically draw the mapped results to the surface using tcl in tksurfer, the color range of the scale bar is not correctly displayed: it has mono blue or red color. This happens only when the range of the overlay is between 0 and 1.  I then tested using the same data by opening the overlay in tksurfer GUI interface and then set the min and max in the view -> configure -> overlay, I find the color of the scale bar makes sense in this way (see the right one in the attached figure). I wonder if someone would help me on this. Did I do something wrong?  The following is the tcl script I used to draw color bar automatically:

I first calculated FS_TKFMAX for the overlay, which is 1 in this case

xmax="1"

FS_TKFMAX=${xmax} ; export FS_TKFMAX

# load the overlay
echo " set overlayflag 1 " > ${1}/${fold_base}${net_den}/script.tcl
echo " set val ${1}/${fold_base}${net_den}/${hemi}.${meas}.mgh " >> ${1}/${fold_base}${net_den}/script.tcl
echo " sclv_read_from_dotw 0" >> ${1}/${fold_base}${net_den}/script.tcl

echo " set colscalebarflag 1 " >> ${1}/${fold_base}${net_den}/script.tcl
echo " set fthresh 0 " >>  ${1}/${fold_base}${net_den}/script.tcl
echo "redraw" >> ${1}/${fold_base}${net_den}/script.tcl
echo "save_tiff ${1}/${fold_base}${net_den}/${hemi}.${meas}_lateral.tif " >> ${1}/${fold_base}${net_den}/script.tcl

tksurfer ${2} ${hemi} inflated -tcl ${1}/${fold_base}${net_den}/script.tcl

Thank you very much in advance!

Leon