Adding to cart not working properly

<?php

function hikashop_characteristics_html(&$element,&$params, &$obj){
		if(empty($element->main->characteristics)) return '';
		$obj->characteristics=&$element->main->characteristics;
		foreach($obj->characteristics as $k => $characteristic){
			if(empty($obj->characteristics[$k]->characteristic_display_method)){
				$obj->characteristics[$k]->characteristic_display_method = $params->get('characteristic_display');
			}
		}
		$obj->load();


		if(empty($html)){
			switch($params->get('characteristic_display')){
				default:
				case 'radio':
				case 'dropdown':
					$main_html = '<div class="hikashop_product_characteristics_table">';
					$config =& hikashop_config();
					foreach($obj->characteristics as $characteristic){
						$main_html.='<div class="hikashop_characteristic_line_'.$characteristic->characteristic_id.'">';
						$values = array();
						$switch_done = false;
						if(!empty($characteristic->values)){
							foreach($characteristic->values as $k => $value){
								if(!$config->get('show_out_of_stock',1)){
									$hasQuantity = false;
									foreach($element->variants as $variant){
										foreach($variant->characteristics as $variantCharacteristic){
											if($variantCharacteristic->characteristic_id==$value->characteristic_id){
												if($variant->product_quantity != 0){
													$hasQuantity = true;
												}elseif( $element->product_id==$variant->product_id && !$switch_done){
													if($characteristic->characteristic_display_method == 'dropdown'){
														$id = 'hikashop_product_characteristic_'.$characteristic->characteristic_id;
														$js = "hikashopUpdateVariant(document.getElementById('".$id."'));";
													}else{
														$id = 'hikashop_product_characteristic['.$characteristic->characteristic_id.']';
														$js = "var el = document.querySelector('[name=\"".$id."\"]'); if(el) el.checked = true; hikashopUpdateVariant(el);";
													}

													$js = "
													window.hikashop.ready( function() {".$js."});";
													if (!HIKASHOP_PHP5) {
														$doc =& JFactory::getDocument();
													}else{
														$doc = JFactory::getDocument();
													}
													$doc->addScriptDeclaration("\n<!--\n".$js."\n//-->\n");
													$switch_done = true;
												}
											}
										}
									}
									if(!$hasQuantity) continue;
								}
								$values[$k]=$value->characteristic_value;
							}
						}


						$html=$obj->display(@$characteristic->characteristic_id,@$characteristic->default->characteristic_id,$values,$characteristic->characteristic_display_method);
						if($params->get('characteristic_display_text') && isset($characteristic->characteristic_value)){
							$html=$characteristic->characteristic_value.'</div><div class="col-md-9">'.$html;
						}
						$main_html.='<div class="row"><div class="col-md-3">'.$html.'</div></div>';
					}
					$main_html.='</div></div>';
					$html = $main_html;
					break;
			}
		}
		$html.='
		<noscript>
			<input type="submit" class="btn button" name="characteristic" value="'.JText::_('REFRESH_INFORMATION').'"/>
		</noscript>';
		return $html;
	}