xgamma doesn't work

[newbie_es]

I have a geode lx800 using tinycore 2.4

I am using Xorg server and the geode graphic driver in "xorg.conf".

I can't get worked the xgamma app.

If I try the command "xgamma -gamma 5" the response is:
-> Red  1.000, Green  1.000, Blue  1.000
<- Red  1.000, Green  1.000, Blue  1.000

Even if I try to set the gamma in the xorg.conf file, in the Xorg log is loaded the value successfully, but the gamma is not changed on the screen.

I think it may  be a buf of the geode driver, but looking through the code, it seems it's ok.

Any suggestion would be appreciated.

[newbie_es]

One more thing:

If I use "vesa" driver, the response to the command "xgamma -gamma 5" is:
-> Red  1.000, Green  1.000, Blue  1.000
<- Red  5.000, Green  5.000, Blue  5.000

But the gamma remains the same.

Do anyone have the same problem even with a different graphic card?