how to play US games on Homebrew with Wii system 4.0E

hi there, I recently downloaded the hbc in order to try to make my wii region free. My wii is European and I have games which are region coded for US. My wii is running on system version 4.0E. I downloaded and installed hbc without problem, but now i can't make it region free. i have also downloaded and tried the geckoOS but when i try to load the game it says 'error: non dvd' and menu loader, when opened just says error.
Is there a way to play US region games on my EUR console operating on system 4.0?
If not, is there any way to downgrade back to system 3.2?
Can somebody help me?

Thanks for reading,
Samson

Which version of Gecko OS are you using? Which games are you trying to play? I heard some games won't run with Gecko OS.

First of all: Downgrading is incredibly dangerous and usually pointless. Also try the latest version of Gecko OS?

What kind of a DVD is it?

NEVER downgrade. It'll definetly brick newer Wiis, and could easily brick older ones. And there is no need for it.

Thanks for the input.
I am using Gecko OS 1.07b. Also tried OS 1.9.1 - but that didn't even work with my PAL DVDs!
Games are Simpsons, Dodge Ball, Call of Duty and others.
Tried adjusting some of the CONFIG OPTIONS but that didn't work so I set them back to the deafault settings.
Any ideas what else I can try?
Thanks,
Samson

These are retail discs, right?

yeah, i bought them in a store