一个href链接在模态弹出按钮中不起作用

Question

我想重定向到某个页面，我在图像和按钮中给出了相同的链接，但对于按钮它根本不起作用。

  <div class="modal fade" id="signModal" role="dialog">
    <div class="modal-dialog">
      <div class="modal-content">
        <div class="modal-body signUpPop">
         <form id="form3" name="form3" method="POST">
          <div class="row loginRow">
            <h4><?php echo $this->lang->line('Log in'); ?></h4>

            <div class="col-sm-6">
               <a href="<?php echo base_url();?>signup">  <img src="<?php echo base_url();?>images/sign-img.png" class="image-responsive"></a>
               <a href="<?php echo base_url();?>signup"> 
             <button  class=""><?php echo $this->lang->line('Sign Up'); ?></button>
               </a> 
            </div>
            <div class="col-sm-6">
              <input type="email" name="email" placeholder="<?php echo $this->lang->line('Email'); ?>" id="email">
              <input type="password" name="password" placeholder="<?php echo $this->lang->line('password'); ?>" id="password">
              <div class="text-right">
               <!--  <span><?php echo $this->lang->line('Forgot Password'); ?></span> -->
              </div>
              <button id="login" type="button"><?php echo $this->lang->line('Log In'); ?></button>
            </div>
          </div>
          </form>
        </div>
      </div>
    </div>
  </div>

我尝试了很多但是，href链接适用于图像但不适用于按钮。

 <div class="col-sm-6">
                   <a href="<?php echo base_url();?>signup">  <img src="<?php echo base_url();?>images/sign-img.png" class="image-responsive"></a>


                   <a href="<?php echo base_url();?>signup"> 
                 <button  class=""><?php echo $this->lang->line('Sign Up'); ?></button>
                   </a> 
                </div>

任何人都可以建议吗？

的config.php

$ config ['base_url'] ='http://localhost/techcampus';