IE错误的提交按钮

我已经为我的梦幻足球网站创建了一个团队构建器。它在Chrome和Firefox上运行良好，但在IE上不行。当我在IE上按下其中一个提交按钮时，整个页面在该框架中重新加载，而不是该框架中的内容。

测试站点链接:http://fantasysoccerpro.com/project/test-ny/

IE bug截图:http://fantasysoccerpro.com/iebug.jpg

//SELECT GOALKEEPER//
$database = "wp_fsprowpdatatable_3";
$goalkeeper="SELECT * FROM `fantasys_fspro`. `$database` where POSITION =     'G'";
$gk = mysqli_query(  $con, $goalkeeper );
?>
  <!-- Example row of columns -->
    <form method="post" action=" ">

        <select name="gk_">
        <option>----------Please Select G----------</option>
  <?php while($gkrow = mysqli_fetch_array($gk))
{ ?>
<option value="<?php echo $gkrow['wdt_ID'];?>"> <?php echo    $gkrow['player'];?></option>
<?php }?>              
        </select>
      </div>

      <button type="submit" class="btn btn-info" name="register" >Submit</button>

    </form>
<?php
if(isset($_POST["register"]))
{
$gk_=$_POST["gk_"];
if ($gk_ > "0") {$selectedgk=$gk_;
}}
//UPDATE TABLE WITH GOALKEEPER//

$sql = "UPDATE $pw 
SET PLAYER= (SELECT PLAYER 
         FROM $database
         WHERE wdt_ID=$gk_) WHERE id = 1";
if ($gk_ > "0") {
if ($con->query($sql) === TRUE) {
} else {
echo "Error updating record: " . $con->error;
}}
$sql = "UPDATE $pw
SET SALARY= (SELECT SALARY 
         FROM $database
         WHERE wdt_ID=$gk_) WHERE id = 1";
if ($gk_ > "0") {
if ($con->query($sql) === TRUE) {
} else {
echo "Error updating record: " . $con->error;
}}
$sql = "UPDATE $pw 
SET PROJECTION= (SELECT PROJECTION
         FROM $database
         WHERE wdt_ID=$gk_) WHERE id = 1";
if ($gk_ > "0") {
if ($con->query($sql) === TRUE) {
} else {
echo "Error updating record: " . $con->error;
}}