问题是解决方案失去了绑定.这就是为什么在添加新项目时它不会自动签出的原因.

The problem is the solution has lost its binding. That's why it's not checking out automatically when you add the new project.

为了在VS 2010中还原绑定，请转到文件"->源代码控制"->更改源代码控制".查找解决方案:您的解决方案名称"，如果未绑定，则会显示"no server".单击它，然后从工具栏中单击绑定".

In order to restore the binding in VS 2010, go to File->Source Control->Change Source Control. Look for the "Solution: your solution name" and if it's not bound it will say "no server". Click on it and then click "Bind" from the toolbar.

在Visual Studio 2012/2013中，它是File-> Source Control-> Advanced -> Change Source Control(感谢danglund).

in Visual Studio 2012/2013 it's File->Source Control->Advanced->Change Source Control (Thanks to danglund).

这应该创建一个正确绑定的新vssscc文件.现在添加新项目，一切都将正常运行.

This should create a new vssscc file that is correctly bound. Now add the new project and everything should work correctly.