fclose警告:fclose(）:提供的参数不是有效的流资源

我在页面上收到警告

警告：fclose（）：提供的参数不是有效的流资源

使用以下代码

$fp = fopen('data.txt', 'w');
$write = '2';
fwrite($fp, $write);
fclose($fp);  

更新代码

if(isset($_REQUEST['go1']))
{
    $fp = fopen('data.txt', 'w');
    $write = '1';
    $fp1 = fopen('file.php', 'w');
    $write1 = '<br><img src="/1/online.png" style="position:absolute; z-index:-2;" />';
}
if(isset($_REQUEST['go2']))
{
    $fp = fopen('data.txt', 'w');
    $write = '2';
    $fp1 = fopen('file.php', 'w');
    $write1 = '<br><img src="/1/offline.png" style="position:absolute; z-index:-2;" />';
}
fwrite($fp, $write);
fclose($fp);
fwrite($fp1, $write1);
fclose($fp1);
$fp = fopen('data.txt', 'r');
$contents = fread($fp, filesize('data.txt'));
fclose($fp);
if($contents == '1')
    include('file.php');
else if($contents == '2')
    include('file.php');
else
    echo 'Something else...';

得到第27行和第29行的错误第27行

fclose($fp);    

线路29

fclose($fp1);