Don't try to read brightness values when only targetting max bright.

src/light.c

   }
 
   /* No need to go further if targetting mincap */
-  if(light_Configuration.field == LIGHT_MIN_CAP)
+  if(light_Configuration.field == LIGHT_MIN_CAP ||
+     light_Configuration.field == LIGHT_MAX_BRIGHTNESS)
   {
     return TRUE;
   }