I have a simple linq lambda statement

Interactions = new BindableCollection<InteractionDTO>(ctx.Interactions.Where(x =>
x.ActivityDate > DateTime.Today)
   .Select(x => new InteractionDTO
   {
       Id = x.Id,
       ActivityDate = x.ActivityDate,
       subject = x.Subject,
       ClientNames = x.Attendees.Count == 1 ? x.Attendees.FirstOrDefault().Person.CorrespondenceName
:
      
x.Attendees.FirstOrDefault().Person.CorrespondenceName : "Multiple attendees"
    }));
This will give me the first Client Name, I'm trying to have
it appear First 2 attendees followed by dots. I tried this
ClientNames = x.Attendees.Count == 1 ? 
            
x.Attendees.FirstOrDefault().Person.CorrespondenceName :
            
x.Attendees.FirstOrDefault().Person.CorrespondenceName +
            
x.Attendees.Skip(1).FirstOrDefault().Person.CorrespondenceName + "
..."

But I get this error:

The method 'Skip' is only supported for sorted input in LINQ to Entities. The method 'OrderBy' must be called before the method 'Skip'.