PHP中的fopen / fputcsv返回true但不写

Question

我只需要在csv上写一行：

//write entery to csv
$file = fopen("valentines.csv","a+");

//values
$values = array(
    $queryParams['firstName'],
    $queryParams['lastName'],
    $queryParams['email'],
    $queryParams['valentine'],
    $queryParams['message']
);

$writeCsv = fputcsv($file,$values);

fclose($file);

return array('success'=>true,'fopen'=>$file,'fputcsv'=>$writeCsv,'exists'=>file_exists("valentines.csv"),'readable'=>is_readable("valentines.csv"),'writeable'=>is_writeable("valentines.csv"));

返回仅用于调试。这是返回的内容：

exists:true
fopen:null
fputcsv:91
readable:true
success:true
writeable:true

当我检查文件时，那里只有一行，我在导入时手动添加到标题中。