unreachable code error Dosent seem right!

Assets/Scripts/Player/Mission Over Gui.js(14,1): BCW0015: WARNING: Unreachable code detected. this error dosent seem right, it works perfectly! thats the error I get for this code:

function GetMedal(a : float){
var ar : float = _G.CurrentMissionStatus.ra;
var rank : int=0;
if (a >= ar){rank+=3;}
else if (a >= ar/2) {rank+=2;}
else if (a >= ar/3) {rank++;}
if (_G.CurrentMissionStatus.Kills >= _G.CurrentMissionStatus.rk) {rank+=3;}
else if (_G.CurrentMissionStatus.Kills >= Mathf.Round(_G.CurrentMissionStatus.rk/2)){rank+=2;}
else if (_G.CurrentMissionStatus.Kills >= Mathf.Round(_G.CurrentMissionStatus.rk/3)){rank++;}
switch(rank){//suposed error here
case 0:
    _G.CurrentMissionStatus.medal = 0;
    return "No Medal Awarded";
    break;
case 1:
    _G.CurrentMissionStatus.medal = 1;
    return "Bronze Medal Awarded";
    break;
case 2:
    _G.CurrentMissionStatus.medal = 1;
    return "Bronze Medal Awarded";
    break;
case 3:
    _G.CurrentMissionStatus.medal = 2;
    return "Silver Medal Awarded";
    break;
case 4:
    _G.CurrentMissionStatus.medal = 2;
    return "Silver Medal Awarded";
    break;
case 5:
    _G.CurrentMissionStatus.medal = 3;
    return "Gold Medal Awarded";
    break;
case 6:
    _G.CurrentMissionStatus.medal = 3;
    return "Gold Medal Awarded";
    break;
}
}

thanks