Php Slim显示“找不到类”错误，即使类存在

我有一个文件Sample.php，其中需要另一个文件Sample2.php。我的目录结构如下：

\main directory
   \vendor
        \Sample2.php
   \Sample.php
   \myFile.php`

Sample2.php的名称空间声明为

namespace MySample\Practice

。 但是当我将Sample2.php作为

use MySample\Practice\Sample2.php

打开流时出现错误失败：没有这样的文件或目录。我认为它无法加载自动加载文件。另外，

myFile.php

有相同的代码，但它正在工作，

Sample.php

中的代码有一些额外的东西不工作。我该怎么办

Sample.php

 use MySample\Practice\Sample2.php;
 $sample2=new Sample2();
 $sample->myFunction();
 //Some other code over here.

 namespace MySample\Practice;
 class Sample2{
     function_construct(){}
     function myFunction(){}
}

 use MySample\Practice\Sample2.php;
 $sample2=new Sample2();
 $sample->myFunction();

Sample2.php

 use MySample\Practice\Sample2.php;
 $sample2=new Sample2();
 $sample->myFunction();
 //Some other code over here.

 namespace MySample\Practice;
 class Sample2{
     function_construct(){}
     function myFunction(){}
}

 use MySample\Practice\Sample2.php;
 $sample2=new Sample2();
 $sample->myFunction();

正常工作的代码myFile.php

 use MySample\Practice\Sample2.php;
 $sample2=new Sample2();
 $sample->myFunction();
 //Some other code over here.

 namespace MySample\Practice;
 class Sample2{
     function_construct(){}
     function myFunction(){}
}

 use MySample\Practice\Sample2.php;
 $sample2=new Sample2();
 $sample->myFunction();

增加

require\u once\uuuuuu DIR\uuuuuuu.'/供应商/autoload.php'

它工作得很好。
如果不显示任何代码，你只能希望自己不会被否决。@NigelRen更新了问题。你是否有一行类似于
require\u once\u DIR\uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu/供应商/autoload.php'（目录可能不同）在任何文件中？不，在任何文件中都没有这样的行