Description of the Bug
I am unable to fill a tankcart with a fluid loader. Rightclicking the cart with a waterbucket also does nothing. The Tankcart itsels also does not show a UI after rightclicking it with an empty hand.

To Reproduce

1. Place tank cart on a track
2. Place Fluidloader directly above the cart
3. Fill Fluidloader with water (has to be through a tank or something similar, becouse the Loader also doesn't accept buckets)

Expected behavior
The tankcart fills with water

Screenshots & Video

Environment
Railcraft 12.0.0-beta2
forge 14.23.5.2796

duplicate of #1549

I think there was an misunderstanding. My problem is not that I can't pump water into the Fluidloader, which is possible (See screenshot). But rather that ich can't pump fluids into the Tankcart at all.

Updated that issue to include the detail you want.