Laravel 419 Page Expired while submitting a form

While submitting a form on a pop-up modal the page gets expired on laravel, I am sending a post request. Can someone please help? i have added a csrf token too..

View Blade

<div id="reviewModal-" class="modal fade" role="dialog">
   <div class="modal-dialog">
      <!-- Modal content-->
      <div class="modal-content">
         <div class="modal-header" >
         </div>
         <div class="modal-body">
            <form id="ecgreviewform" class="ecgreview" action="" method="POST">
               @csrf 
               <div class="col-md-6">
                  <div class="form-group">
                     <input type="text" class="form-control" placeholder="tesdt" id="exampleInputEmail1" aria-describedby="emailHelp" value="">
                  </div>
               </div>
   <div class="modal-footer">                                                        
   <div class="row">
   <div class="col-md-6">
   <button type="button" style = "width:50%;" class="btn btn-primary btn-outline-blue btn-close-modal" data-dismiss="modal">Cancel</button>                                                
   </div>
   <input type="hidden" name="participant_id" value="">
   <div class="col-md-6">
   </div>
   </div>    
   <button type="submit" form="ecgreviewform" style = "width:50%;" name="submit" value="submit" class="btn btn-primary">Save</button>  
   </form>
   </div>
</div>
</form>
</div>`
</div>

Route page

Route::get('ecg/pendingreview', 'EcgReviewController@index')->name('ecg.pendingreview');
 Route::post('ecg/pendingreview', 'EcgReviewController@store')->name('ecg.reviewstore');

is there any reason

via Chebli Mohamed