So I got some see through clouds to work on a plane in UDK. I plugged a texture node into the diffuse input and a duplicate texture node into the opacity input. Boom, works like a charm. However it won't show in mobile previewer. You are saying it might actually work in real game even though the mobile previewer won't pick…
Yes the previewer can't handle various advanced setups well but you should probably get at least part of it working, or at the very least you should see SOMETHING happening, even if it not entirely correct. However when you say you "plugged it into diffuse input" it makes me think you are using the expression/shader…