쇼핑몰 카테고리 javascript 코드 포함 재질문

<script type="text/javascript">

function productChange_top(p) {

var o_outer=["PADDING","COAT","JAKET"];

var t_top=["SHIRT","1/2 T=SHIRT","T-SHIRT","HOODY","KNIT"];

var b_bottom=["DENIM","SLACKS","SHORT PANTS","COTTON PANTS"];

var s_shoes=["SNIKERS","BOOTS","LOAFERS"];

var midoption=document.getElementByID("productmiddle");

if (p.value=="O") var m = o_outer;

else if (p.value=="T") var m = t_top;

else if (p.value=="B") var m = b_bottom;

else if (p.value=="S") var m = s_shoes;

mid_option.options.length=0;

var count=1;

var opt = document.createElement("option");

opt.value="";

mid_option.appendChild(opt);

for (x in m) {

var opt=document.createElement("option");

opt.value=p.value+x;

opt.innerHTML=m[x];

mid_option.appendChild(opt);

}

}

function pnumValue() {

var pval=productChange_top.value;

document.getElementById('pnum').value=pval;

}

</script>

스크립트 부분입니다

<tr>

<td>상품 분류</td>

<td><select name="producttop" id="producttop" class="productselecttop"

onchange="productChange_top(this)" required="required">

<option value="O">OUTER</option>

<option value="T">TOP</option>

<option value="B">BOTTOM</option>

<option value="S">SHOES</option>

<option value="A">ACC</option>

</select>

<select name="pnum" id="product_middle" onchange="pnumValue(this)"

class="productselectmiddle">

</select></td>

</tr>

html 부분입니다 왜 저 옵션들을 누르면 스크립트 부분으로 안 넘어가질까요ㅜㅜ