Dear FreeSurfer expert

I am trying to create a mask for the right hemisphere frontal lobe cortex in order to calculate the mean cortical thickness for this specific ROI.

I am using the following commands:

To create a mask for the specific region:  
mri_binarize --i /mri/aparc+aseg --match 2028 --match 2027 --match 2003 --match 2024 --match 2018 --match 2020 --match 2019 --match 2014 --match 2032 --match 2002 --match 2026 --o /mri/rh_frontal_ctx.mgz

But I am not sure what the next step is -

I tried to follow this link: https://surfer.nmr.mgh.harvard.edu/fswiki/VolumeRoiCorticalThickness (Cortical Thickness of a Volume-defined ROI)
fslregister --s fsaverage --mov /mri/T1.mgz --reg T1_to_fsaverage.dat
but I am not sure if that is the correct way, and also my ROI in the fsaverage subject volume is not perfectly matched to what I expect it to be - how can I fix that? They are very different.

I also tried the mri_tessellate command to create surface by tessellating given input volume:
mri_tessellate /data/Temp_efrat/subjects/TB_281_test/mri/rh_frontal_ctx_1.mgz -a 2028 2027 2003 2024 2018 2020 2019 2014 2032 2002 2026 frontal_ctx_test

I get this massage:
changing type of input volume to 8 bits/voxel...
$Id: mri_tessellate.c,v 1.32 2007/04/26 21:44:21 fischl Exp $
  $Id: mrisurf.c,v 1.557.2.19 2009/08/05 22:10:21 nicks Exp $
slice 110: 431 vertices, 495 faces
slice 120: 2986 vertices, 3215 faces
slice 130: 6636 vertices, 7037 faces
slice 140: 12817 vertices, 13506 faces
slice 150: 22361 vertices, 23291 faces
slice 160: 32454 vertices, 33549 faces
slice 170: 44058 vertices, 45346 faces
slice 180: 56174 vertices, 57633 faces
slice 190: 67020 vertices, 68612 faces
slice 200: 75820 vertices, 77402 faces
slice 210: 78847 vertices, 80236 faces
slice 220: 78900 vertices, 80278 faces
slice 230: 78900 vertices, 80278 faces
slice 240: 78900 vertices, 80278 faces
slice 250: 78900 vertices, 80278 faces
using the conformed surface RAS to save vertex points...
writing 2028
using vox2ras matrix:
-1.000   0.000   0.000   128.000;
 0.000   0.000   1.000  -128.000;
 0.000  -1.000   0.000   128.000;
 0.000   0.000   0.000   1.000;

But I can not find the output file of that command.

And then to calculate the thickness of the frontal cortex by using the
mris_anatomical_stats TB_281_test  rh -t frontal_ctx_test

I am a little confused, I will be grateful if you can help me with that.

Thanks a lot

Efrat