I have the following web-method:

```
namespace MessageService{
...
    [WebMethod]
    public ServiceReturnCodes SetMsg(List<Guid> Ids, DateTime processDateTime)
    {
        BL.SetMsg(Ids, DateTime.Now);   
    }
}

```

But when I call this method:

```
public List<Guid> Ids = new List<Guid>();
...
service.SetMsg(Ids, DateTime.Now);

```

I get the following error: Argument '1': cannot convert from 'System.Collections.Generic.List' to 'MessageWeb.MessageService.ArrayOfGuid'
I can't figure out what `ArrayOfGuid` is and why it tries to convert.