Could you post a screen shot of the area.
Have the ambience at 5 and the color of the ambience to be r 10 g 10 b 10. at this point there should be rather little ambient light and the only light you should see good is any lights you have placed in the level.
If it is to bright then reduce the luminance of the light to 50% of light. maybe reduce the range of the light also.
If it is to dark then either raise the lumance of the light or increase there range.
At this point you can start to mess with the ambient setting more.
Also check the setup.ini file and make sure the setting are close to what I have listed. these changes in the makegame section will effect your light maps
[GAMERUN]
realgameview=0
dynamiclighting=1
dynamicshadows=0
useeffects=1
useeffectsonguns=1
useeffectsonscene=1
useeffectsonentities=1
dividetexturesize=2
controllerhint=0
vrmode=0
vrmodemag=100
mousesensitivity=100
producelogfiles=0
hsrmode=2
optimizemode=1
aspectratio=0
newblossershaders=1
postprocessing=0 <-- 1 bloom 2 DOF
showaioutlines=0
disablepeeking=0
[GAMEMAKE]
lightmapping=1
lightmapold=0
lightmapshadows=0
lightmapambientr=0
lightmapambientg=0
lightmapambientb=0
lightmapsunx=0
lightmapsuny=-1
lightmapsunz=0
lightmapsunr=0
lightmapsung=0
lightmapsunb=0
lightmapzerorange=100
lightmapatten=16
lightmapmaxsize=-1
lightmapboost=4
lightmaptexsize=512
lightmapquality=35
lightmapblurmode=1
lightmapthreadmax=-1
bloodonfloor=0
imageblockmode=1
showalluniquetextures=0
If you are going to use the bloom shader at all you should reduce the luminance of the lights even more maybe. Depends on you taste.
If this all fails then you might need to brighten or darken certian textures in your map level. start with the _S and _I textures as they seem to effect the brightness of most shaders.
The community guide has a section pertaining to lighting. Well worth reading. Hope this helps more.
Nothing but coffee in my veins 'Insomnia is Coming'