How to correctly perform dependency injection in the .net6 api project?

[y1meng]

I added the code according to the example in the wiki:

//MediatR
builder.Services.AddMediatR(cfg => {
    cfg.RegisterServicesFromAssembly(typeof(Program).Assembly);
});

I added Notifications at first, but it didn't work, then I changed to Request, and finally got the error message: "One or more errors occurred. (No service for type 'MediatR.IRequestHandler`1"

Below is all my code, what am I missing? Thanks for any help

    public class DeviceInfoUpdate : IRequest
    {
    }

   public class DeviceInfoSyncRegional : IRequestHandler<DeviceInfoUpdate>
   {
      public Task Handle(DeviceInfoUpdate notification, CancellationToken cancellationToken) {
          Console.WriteLine("ok...");
          return Task.CompletedTask;
     }
  }

//send
_mediator.Send(new DeviceInfoUpdate()).Wait();