SOLVED -- SCT (set color temperature) not working???

[p1d]

As the title says, I am having problems with SCT on a newly built system. With my old system, SCT works just fine, but with this new system, SCT (and also REDSHIFT) do not work at all. Issuing a "sct 2700" (or any other temperature) from the terminal does nothing, no errors reported. Tried "redshift -O 2700" also does not work... but does return the following:

Gamma ramp size too small: 0

Failed to start adjustment method randr.

Trying next method...

Using method `vidmode'.

... and then returns to the terminal prompt.

System Information:

CPU: AMD Ryzen 5 3400G

Monitor: Viewsonic XG2705-2K

OS: Debian 10 (Buster), Kernel 4.19.0-14, Mate 1.20.4

Any help or suggestions would be much appreciated.

[Head_on_a_Stick]

What is your graphics hardware and driver? Have you installed any non-free firmware that is required?

[p1d]

SOLVED!

Thanks to Head_on_a_Stick, this is SOLVED!!!

Problem was: not having non-free firmware installed.

SOLUTION: Via Synaptic, go to Settings>Preferences>Distribution, and select: prefer versions from buster-backports. Then reload the repositories, and install: firmware-amd-graphics

SCT now works as intended.

Thanks again, Head_on_a_Stick!!!