Notice: Undefined variable: backup.tpl on line 43 – Opencart

<file path="admin/view/template/tool/backup">
      <operation>
         <search><![CDATA[
            <label class="col-sm-2 control-label"><?php echo $entry_export; ?></label>
            ]]></search>
         <add position="replace">
            <![CDATA[
         <label class="col-sm-2 control-label"><?php echo $entry_backup; ?></label>
            ]]>
         </add>
      </operation>
   </file>

Simply replace Line 43

<?php echo $entry_export;

for

<?php echo $entry_backup;