Yes: Check carefully for any other buildings within your station's service radius that can demand iron or coal. For some ranges of years, that includes houses because towns demand coal. You might need to place a new depot so that it can only deliver to the steel mill.
A few things added this time:
-Added: Second version of the dune 2 based campaign (3 houses) using a custom dune 2 tileset for Dune 2000.
-Single map added: D2K Atreides mission 1B using the Dune 2 tileset By sayedmamdouh.
-Single map added: Harkonnen mission 8 but as Mercenaries By sayedmamdouh.
-New Misc added: Dune 2 Tileset For dune 2000 - By Cm_Blast
-Link Fixed: War of Assasins campaign now point to the post with the mission launcher that includes that campaign, since the original post doesn't contain a valid link or download anymore; it is possible to read what the campaign it's about on the "more info here" sub-link. This will be provisional until his author repost the campaign.