C# AD group count not correct

Question

I am writing my first code to read all the members of an AD group and am not getting the correct number of group members:

public static void GetListOfAdUsersByGroup (string domainName, string groupName) {

   PrincipalContext ctx = new PrincipalContext (ContextType.Domain);        // Set up the domain context
   GroupPrincipal group = GroupPrincipal.FindByIdentity (ctx, groupName);   // Find the specified group

   if (group != null) {
      foreach (Principal p in group.GetMembers()) {
         Console.WriteLine ("{0}: {1}", p.StructuralObjectClass, p.DisplayName);
      }
   }


}

Already I have a problem. group.Members.Count is 3 and I print those 3 members, but the number should be much larger. What could I be doing wrong so early?

EDIT: I am getting two errors in the Output window right before my 3 users are listed. The errors are:

Exception thrown: 'System.ArgumentException' in mscorlib.dll Exception thrown: 'System.FormatException' in mscorlib.dll

EDIT 2:

I basically stole the following code from somewhere else, and am also getting 3 results from this code as well!

public static IEnumerable<string> GetGroupMemberList (GroupPrincipal group, bool recursive = false) {
    using (var memberPrincipals = group.GetMembers(recursive)) {
        foreach (Principal member in memberPrincipals) {
            yield return member.SamAccountName;
        }
    }
}

Calling like this:

PrincipalContext ctx = new PrincipalContext (ContextType.Domain);
GroupPrincipal group = GroupPrincipal.FindByIdentity (ctx, "DOC.WKCC");
_elements = new List<string>(GetGroupMemberList (group, true));