Result of transmission fuction

I am trying to calculate the transmission function and get a strange result, the curve has many 90-degree turns.

I think it is evident that there are some issues in my calculation.I suspect it might be due to the K-point settings in TBtrans calculations.
However, when I try to change it using “TBT.k” set
“%block TBT.k
diag 3 3 10
in the .fdf file.
but in tbt.log, the kpoint in the transmission direction is unchange as the follow:
Kpoints in: 6 . Kpoints trimmed: 5
tbt: Number of transport k-points = 5
tbt: Method = Monkhorst-Pack grid.
tbt: k-grid: Supercell and displacements
tbt: 3 0 0 0.000
tbt: 0 3 0 0.000
tbt: 0 0 1 0.000

Does anyone know where my calculation error might be?

Any help would be greatly appreciated.
scat.fdf (4.7 KB)

It looks correct. Electrodes and scattering region are (probably) identical and so the transmission function is step like.