[Sascha]

your code is wrong (if that is your whole code)

pawn Код:

public OnPlayerKeyStateChange(playerid, newkeys, oldkeys)
{
    if(PlayerKilled[playerid] == 1)
    {
        if(IsKeyJustDown(KEY_SPRINT,newkeys,oldkeys))
        {
            TogglePlayerSpectating(playerid, 0);
            PlayerSpectating[playerid] = 0;
            PlayerKilled[playerid] = 0;
            TextDrawHideForPlayer(playerid, txtSpec);
        }
        if (PRESSED(KEY_LOOK_BEHIND))
        {
            SendClientMessage(playerid, COLOR_BLUE, "You take the point");
            return 1;
        }
    }
    return 1;
}

Additionally to get sure what is stopping your script, add "SendClientMessage(playerid, 0x999999AA, "Called 1");" before "if(PlayerKilled.....)"
and "SendClientMessage(playerid, 0x999999AA, "Called 2");" below that line (below the } ofc)...

I suppose your "IsKeyJustDown" is not working correctly