Bug: Cargo station conected to concrete plant can't be used by construction offices?

[c_vld_c]

As the title says, I built my cement plant with a cargo station so I wouldn't have lines for the concrete trucks, but the construction office doesn't seem to be able to use it. The cargo station says it has access to concrete, so I think this is just a bug for the construction office.

The error message says that the station needs to be connected to a storage facility, but there's no such thing for concrete. What do I do?

Image to explain the situation better:
https://imgur.com/dNtYhFE

[bodnar.pet]

concret plant don't have storage for concret, you must use plant as source
depot should be used as SOURCE for cement/gravel

[melkij]

This factory connection was used to supply cement before the introduction of the dry conveyor in the game (remained in place so as not to break old saves for people). The produced concrete is loaded directly at the plant itself. Point the construction office to the plant itself.

[esbenmf]

The cargo connection at the concrete plant is (an old from before dry-bulk conveyors) workaround to PROVIDE cement for the plant, NOT to pick up concrete.

[ryantheskinny]

The concrete plant has to mix it. Its not possible to load it any other way.