[Why ?] tankbusta have rokets but doesnt shoot (they are not in "stop fire" mode)

[jeantend]

here the replay :
http://jeantend.free.fr/fourtou/wh40k.dow/why_dont_they_shoot.rec
at 17'43
the 2 squads tankbustas have rokets, shoot 1 time, then stop...
i gave them the order again (twice) to shoot, but nothing, they didnt shoot...

was on dead man crossing, ork vs chaos...