Hey -
You may need to reference the Enum directly. By changing your first function call above to “ECollisionChannel::ECC_WorldStatic” you should get the behavior you’re looking for. Alternatively, by following the example code in the documentation for LineTraceSingle (https://docs.unrealengine.com/latest/INT/API/Runtime/Engine/Engine/UWorld/LineTraceSingle/2/index.html) you could define your own variable as one of the possible results from the Enum and use that instead.
Cheers