With Netflix debuting a number of critically praised -- but costly -- new shows during the quarter ended June 30, analysts had expected a big rise in its subscriber base. And there was such a rise -- 630,000 people signed up for its streaming service. (On the other hand, it lost 470,000 DVD-by-mail subscribers.) The problem was that Wall Street had expected far stronger results, and shares in the company, which have ridden a roller-coaster over the past year or so, were down more than 6 percent at midday today (Tuesday). In a conference call on Monday, Netflix chief Reed Hastings repeated his earlier prediction that the company could eventually sign up 60-90 million subscribers. (It currently has 28.6 million.) However, he added, The larger we get the harder it is to grow.