Search Files with Graph SDK

Hello, I would like to search for a file with the Graph SDK(ASP.Net Core and C#), with Postman this also works as desired.

https://graph.microsoft.com/v1.0/users/{user-id}/drive/root/search(q='Filename')

But I just can't get it to work with the SDK (empty collection).

private async Task<IDriveItemSearchCollectionPage> SearchFiles(GraphServiceClient graphClient){
  var search = await graphClient.Users["User-iD"].Drive.Root
    .Search("Filename")
    .Request()
    .GetAsync();

    return search;
}

And the associated iterator:

 private void PrintFiles(IDriveItemSearchCollectionPage files) {

        foreach(var file in files) {
          var message = $"File: {file.Name}, Id: {file.Id}";

          Console.WriteLine(message);
        }
    }

What am I doing wrong ?

I would be very happy to receive help.

Greetings