How to write query where condition in List of shorts

I have to write a query using C# / LINQ, the equivalent of this:

select RoleName from dbo.Roles where RoleId in (2,3,4,5,6) 

In my code I have a list of short ids (idRoles is a list of shorts ( example: 1,2,3,4)) and this code:

 List<string> roleNameList = new List<string>();

 roleNameList = _dbContext
  .Roles
  .Where(r => idRoles.Contains(r.RoleId))
  .Select(r => r.RoleName);

gives an error:

Cannot convert from System.Linq.IQueryable ‘<‘string’>’ to string.

But in my table Role the IdRole is a short(smallint)

>Solution :

try this

List<string> roleNameList = _dbContext
  .Roles
  .Where(r => idRoles.Contains(r.RoleId))
  .Select(r => r.RoleName)
  .ToList();