L2PcInstance player = (L2PcInstance)activeChar;
if (castle == null || castle.getCastleId() <= 0)
sm.addString("You must be on castle ground to use strider siege assault");
else if (!castle.getSiege().getIsInProgress())
sm.addString("You can only use strider siege assault during a siege.");
else if (!(player.getTarget() instanceof L2DoorInstance))
sm.addString("You can only use strider siege assault on doors and walls.");
else if (!activeChar.isRiding())
sm.addString("You can only use strider siege assault when on strider.");
else