C# - Fill Combo-box Via DataSource Using Values From Various Columns?

Employee emp = new Employee();
comHandledBySQt.DataSource = emp.GetDataFromTable("1");
comHandledBySQt.DisplayMember = "FirstName";

The above code displays drop list of employees first names in a combo box. I want first name and last name to be displayed. How can i do it?I tried to include two columns FirstName and LastName as below but didn't work.

comHandledBySQt.DisplayMember = "FirstName" + " " + "LastName";