When I try to build a screw pump with bMs, I see the red text:

Needs screw trap component

I've already built seven pumps, and still have blocks, pipe sections, mechanisms and enormous corkscrews to go. Nothing is forbidden, and no burrows are activated. What could I be missing?

Edit: It does work now, and AFAIK nothing changed. So the question is: What could I have been missing?


Having items unforbidden is not always enough to make them eligible for constructing buildings.

My guess is that one or more of your Enormous Corkscrews had been scheduled to be picked up (that is to say, there was a dwarf moving towards it) or was being actively moved.

Once your dwarves put down your giant corkscrews, they'll become usable again, as you observed.

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  • I agree, an item being "in use" because it is in transit or even just scheduled to be moved to a stockpile is a common cause of temporary hold-ups like this. – Theodore Murdock May 18 '12 at 21:15

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