temperature profile in the case of Couette flow

Dear Lammps users,

I want to compute the temperature profile in a system including gas molecules confined between two walls. In my system, both walls are being thermostated at 300 K and I insert velocity in -X and +X directions on the bottom and top walls, respectively. Afterward, I calculated per-chunk temperature in the gas domain using both "fix ave/chunk temp" and "compute temp/chunk temp com yes". I was expecting that using "fix ave/chunk temp" temperature in the vicinity of the walls should be higher than 300 K and in the central part of the system it should be around 300 K. Besides that, I was expecting almost constant temperature around 300 k from "compute temp/chunk temp com yes". But as you can see in the attached image "fix ave chunk" gives almost constant temperature (around 300 K) along the microchannel height and, surprisingly, "compute temp/chunk temp com yes" gives temperature less than 300 K in the central parts of the channel.
I highly appreciate if someone could tell me what I am doing wrong here.

##--------Input file

----------------------------------------------------------------------------- INITIALIZATION ----------------------

units metal
dimension 3
boundary p p p
atom_style atomic
lattice fcc ${latparamAu}
region whole block 0 100 0 155 0 100 units box

create_box 2 whole

region Au_B block INF INF 10 19 INF INF units box #Bottom Wall

region Au_T block INF INF 135 145 INF INF units box #Top wall

mass 1 196.97
mass 2 39.95

create_atoms 1 region Au_B

create_atoms 1 region Au_T

group AuB region Au_B

group AuT region Au_T

region Au_B_fix block INF INF 10 11 INF INF units box

region Au_T_fix block INF INF 144 145 INF INF units box

group AuBfix region Au_B_fix

group AuTfix region Au_T_fix

group AuB_thermo subtract AuB AuBfix

timestep 0.001

#----------------------------------------------FORCE FIELD-----------------------------------------------------------
pair_style hybrid eam lj/cut {rc} pair_coeff 1 1 eam Au_u3.eam pair_coeff 1 2 lj/cut {eps_Au_Ar} {sigma_Au_Ar} pair_coeff 2 2 lj/cut {eps_Ar_Ar} ${sigma_Ar_Ar}

neighbor 2 bin

#-------------------------------------------------------Adding Ar atoms


I suggest you try the compute temp/profile command, which can output
the temperature in each bin. It also treats the COM velocity in the correct
manner which is discussed on the doc page. This may be different (as
I recall) than compute temp/chunk.