ok, I got it!!!! the problem was the column names and the way of writing. the fixed is: <code> input = @"INSERT INTO userAuth ([user], [pass], [mail]) VALUES ('" + username + "', '" + pass + "', '" + email + "') "; </code> and the parameters that i sending is after casting ToString(), also, in the DB i changed the Column rule to string and not email column as i defined before. thanks to everyone. ido.