if you created "U"neek2o (neek2o on USB) : do you have the /sneek/ folder and its content on both SD and USB ?
you need to place the folders on both SD and USB !
you need to place your NAND dump to the device you chose (Uneek to USB, Sneek to SD)
You need bootmii IOS installed (if you have a stub IOS254) then you don't have bootmii IOS and that's why it can't launch bootmii.
Did you try to launch Bootmii manually from HBC home menu?
Homebrew channel > Home menu > launch bootmii.
it should launch neek by doing that.
If nothing happens, run syscheck (follow the guide in my signature) to verify you have bootmii installed in IOS slot254.
try another SD card.
Try another USB device (not flash !, only HDD)
try another neek loader (USBLoaderGX does not use bootmii method at all and directly launches neek)