Edited cell was reset after change focus in gridview using devexpress 15.2 c#

i'm newbie in devexpress. when i add new row and fill some value to one cell, then i focus to other cell in same row i lost value in that cell. This is my code (column name in gridview match with coumn in Datatable dtGroupRole)

FrmUser.cs
...
adminGroupRoles = AdminGroupRoles.GetAllGroupRoles().ToList();
dtGroupRole = GlobalVars.ToDataTable<AdminGroupRoles>(adminGroupRoles);
grdGroupRoles.DataSource = adminGroupRoles;


AdminGroupRoles.cs
public class AdminGroupRoles
{
    public int GroupId { get; set; }
    public string GroupName { get; set; }

    public static List<AdminGroupRoles> GetAllGroupRoles()
    {
        return AdminGroupRoles.Inst.ExeStoreToList("sp_AdminUsers_GetAllGroupRoles");
    }
}

The edited cell was reset:

Thanks all :)