Commercial ships usually can't load auto mines

[Automatedminion (OP)]

Repeatedly, I've tried to use civilian contracts to deliver automated mines to various locations.   This has hardly ever worked.

What keeps happening is dozens of ships will rush to Earth, then fail to load the mines.   Then they travel to their destinations, anyway.

I've tried canceling orders; never helps.

[Erik L]

You have a demand contract in place at the destination along with a supply contract at the source?

Example -
Earth has 100 automines.

I want 10 on Mars, 10 on Io and 25 on Ganymede.
I set a supply contract on Earth for 45 automines.

I set 3 demand contracts; one on Mars for 10, one on Io for 10 and one on Gany for 25.

[Automatedminion (OP)]

This is always with the appropriate demand contract at the destination, and a supply contract at the source. 

Perhaps this is a stupid question--but you do have to build the mines yourself, right?

[Erik L]

Yes. If they are not available to be picked up, the freighters will find something else to do.