huh!?

[se5a]

in a game I carefully set up an assult on an enemy plannet. I attacked it with three fleets all with the same movement from the same sector.

but

I lost 10 ships to mines - even though I had enough sweepers in one of the fleets. what happend here???

in the combat log the ships started practicaly on top of the plannet (3 sectors away from the nearest plannet there were 4 plannets alltogether)
why did they do that?