[Dragokas]

If statistics plugin working for you and you don't have any errors in log,
the only convar that enabled aura/color is l4d_hxstat_color_enable, which is defaulted to 1 (enable).

I'm using both in L4D2 at the moment, and I don't have any problems.
Check on a fresh server. Maybe your problem is related to conflict with some other 3rd-party plugin.