Dapper : Mapper Query not getting values where as Dynamic Object Mapper Query does

I am a beginner to dapper . I was going through the code and building samples . But I am having problems in retrieving data . My code is as follows

 Console.WriteLine("Reading Values");
            string readSatement = "select * from employee where Id=@Id ";
             IEnumerable<Employee> objEmp1 = con.Query<Employee>(readSatement,
                 new {
                     Id = empId
                 });

             var objEmp2 = con.Query(readSatement, new { Id = empId }); 

In this code objEmp2 retrieves values from db for the id passed . But objEmp1 gives null values for the attributes of the object .

Employee class is as below

 public  class Employee
    {

      public int EmpId { get; set; }
      public string EmpName { get; set; }
      public int EmpAge { get; set; }
    } 

Whats wrong with the code .