Zenith is a large single player campaign for Unreal Tournament '99. which takes place years after Prisoner 849 escapes from Na'Pali, and long after the establishment of the Tournament.
goes in the textures folder, seems the dev couldnt solve the problem since the beta version. credit goes to unrealsp forum
"Please note that we are not responsible for accomodating for any additional modifications or adjustments that you have made to your Unreal Tournament game."
Source: Zenith.fxgaming.org
it is not a problem with the dev, it is in the disclaimer. Thanks anyway