请教php连接sqite的问题，视频能用，我的不能用

<?php
 $db=sqlite_open("test.db");
 
 if($_POST['submit']) {
  $sql="INSERT INTO test (id,context,time) VALUES(NULL,'$_POST[context]',$_POST[time])";
  sqlite_query($db,$sql);
 }
?>
<form action="" method="post">
标题：<input type="text" name="context" size="40" style="height: 23px" /><br>
年份：<input type="text" name="time" style="height: 23px" /><br>
<input type="submit" name="submit" value="发布内容" />
</form>
错误
Warning: sqlite_open() [function.sqlite-open]: file is encrypted or is not a database in F:\PHP\local\Apache2.2\htdocs\sqlite3\sqlite3.php on line 2

Notice: Undefined index: submit in F:\PHP\local\Apache2.2\htdocs\sqlite3\sqlite3.php on line 5