html5输入日期在帖子php上空

Question

我正在使用HTML5输入日期类型。发布后，我看到此输入为空，所有其他输入（HTML4类型）都可以。

可能是什么原因？

这是我的表格：

<form action="/SGM/index.php?r=manager/addcoach_post" method="post">
        <div class="registerFeildArea2">
            <div class="registerTxtP2">Family name</div>
            <div class="registerFeild">
              <input name="lname" type="text" value="" size="" class="registerFeildValue" />
            </div>
        </div>
        <div class="registerFeildArea">
        <div class="registerTxtP2">First name</div>
            <div class="registerFeild">
              <input name="fname" type="text" value="" size="" class="registerFeildValue" />
            </div>
        </div>
        <div class="registerFeildArea2">
            <div class="registerTxtP2">Address</div>
            <div class="registerFeild">
              <input name="address" type="text" value="" size="" class="registerFeildValue" />
            </div>
        </div>
        <div class="registerFeildArea">
            <div class="registerTxtP2">City</div>
            <div class="registerFeild">
              <input name="city" type="text" value="" size="" class="registerFeildValue" />
            </div>
        </div>
        <div class="registerFeildArea2">
            <div class="registerTxtP2">Birthdate</div>
        <div class="birthDayFeild">
          <input name="bdate" id="meeting" type="date" value="2011-01-13"/>
        </div>
        </div>

        <div class="AddBtn"><input name="Next" type="submit" value="הוסף" class="AddBtnValue" /></div>
    </form>

当我到达actionAddcoach_post()时，除了bdate之外，所有字段都可以。

可能是什么原因？