wpf - update user profile in silverlight -

i create user profile page in silverlight , use wcfria in project write these code doesnt change in database. how can implement page ? code :

//domain service           public void edituser(tbluser user,long id)         {             var query=(mydb.tblusers.where(u=>u.user_id==id).select(u=>u)).single();             try             {                 query.fname = user.fname;                 query.lname = user.lname;                 query.email = user.email;                 query.cnum = user.cnum;                 query.address = user.address;                 query.url = user.url;                 mydb.savechanges();             }             catch             {                 return;             }         }       //code behind :      ctx.edituser(user, id);      ctx.submitchanges();