회원정보입력란에 필수입력사항을 만들려고 하는데

문제는 '이중선택' 항목입니다. required itemname="직장정보" 을 아래처럼 했는데도 안됩니다.

이중선택은 잘돌아갑니다.

어떻게 해야 필수입력사항으로 만들수 있을까요?

(포인트 2000개!! 드려요)

<TR bgcolor="#FFFFFF">
<TD class=m_title>직장정보</TD>
<TD class=m_padding>
<select name="mb_5" required itemname="직장정보" size="1" onChange="redirect(this.options.selectedIndex)" >
<option value="00">선택하세요</option>
<option <? if ($member[mb_5]=="사업체") { echo "selected"; } ?> value="사업체">사업체</option>
<option <? if ($member[mb_5]=="학생") { echo "selected"; } ?> value="학생">학생</option>
<option <? if ($member[mb_5]=="공무원") { echo "selected"; } ?> value="공무원">공무원</option>
<option <? if ($member[mb_5]=="전문직") { echo "selected"; } ?> value="전문직">전문직</option>
<option <? if ($member[mb_5]=="기타") { echo "selected"; } ?> value="기타">기타</option>
</select>
<select name="mb_6" required itemname="직장정보" size="1">
<option value="">선택하세요</option>
<?
if ($member[mb_6]=="해외상장사(국내상장포함)") { $select2_name="해외상장사(국내상장포함)"; }
elseif ($member[mb_6]=="국내거래소상장사") { $select2_name="국내거래소상장사"; }
elseif ($member[mb_6]=="코스닥상장사") { $select2_name="코스닥상장사"; }
elseif ($member[mb_6]=="비상장법인") { $select2_name="비상장법인"; }
elseif ($member[mb_6]=="개인사업자") { $select2_name="개인사업자"; }
elseif ($member[mb_6]=="자영업자") { $select2_name="자영업자"; }
elseif ($member[mb_6]=="NGO/NPO") { $select2_name="NGO/NPO"; }

elseif ($member[mb_6]=="대학원(박사과정)") { $select2_name="대학원(박사과정)"; }
elseif ($member[mb_6]=="대학원(석사과정)") { $select2_name="대학원(석사과정)"; }
elseif ($member[mb_6]=="대학생") { $select2_name="대학생"; }
elseif ($member[mb_6]=="고등학생") { $select2_name="고등학생"; }
elseif ($member[mb_6]=="중학생") { $select2_name="중학생"; }
elseif ($member[mb_6]=="초등학생") { $select2_name="초등학생"; }

elseif ($member[mb_6]=="입법부") { $select2_name="입법부"; }
elseif ($member[mb_6]=="행정부") { $select2_name="행정부"; }
elseif ($member[mb_6]=="사법부") { $select2_name="사법부"; }

elseif ($member[mb_6]=="변호사") { $select2_name="변호사"; }
elseif ($member[mb_6]=="공인회계사") { $select2_name="공인회계사"; }
elseif ($member[mb_6]=="변리사") { $select2_name="변리사"; }
elseif ($member[mb_6]=="법무사") { $select2_name="법무사"; }
elseif ($member[mb_6]=="세무사/관세사") { $select2_name="세무사/관세사"; }
elseif ($member[mb_6]=="경영지도사") { $select2_name="경영지도사"; }
elseif ($member[mb_6]=="기술지도사") { $select2_name="기술지도사"; }
elseif ($member[mb_6]=="감정평가사") { $select2_name="감정평가사"; }
elseif ($member[mb_6]=="통관사") { $select2_name="통관사"; }
elseif ($member[mb_6]=="기술사") { $select2_name="기술사"; }
elseif ($member[mb_6]=="건축사") { $select2_name="건축사"; }
elseif ($member[mb_6]=="도선사") { $select2_name="도선사"; }
elseif ($member[mb_6]=="노무사") { $select2_name="노무사"; }

elseif ($member[mb_6]=="주부") { $select2_name="주부"; }
elseif ($member[mb_6]=="연금소득자") { $select2_name="연금소득자"; }
elseif ($member[mb_6]=="구직자") { $select2_name="구직자"; }
else { $select2_name="선택안함"; }

echo "<option selected value=\"$member[mb_6]\">$select2_name</option>";
?>
</select>
</td>
</tr>