The maker of the Blackberry PlayBook has delayed an update to the tablet computer\'s operating system until next year. Research In Motion said it expects to deliver the software in February. It had been due this month. RIM has admitted that sales of the device are lower than it anticipated. It acknowledged customers want native email, calendar and contacts applications. The update aims to add the features. A company blog described the decision as \"difficult\", but promised the revision will allow the firm\'s phones and PlayBooks \"to work together even better\". RIM\'s shares fell around 6% following the news. Instant messaging At present users cannot access their Blackberry email through the tablet computers unless the devices are linked to one of the firm\'s smartphones using its Bridge software. The Canadian firm also said it had taken the decision to defer the inclusion of a BBM instant messaging application until a later release. However, RIM said it was still planning to offer businesses the ability to manage their employees\' tablets from a centralised computer server and to offer workers custom-built applications through the Blackberry App World store in its OS 2.0 download. Analysts said the news may prove damaging to sales over the holiday season. \"It is a big setback for them. When they launched the tablet they tried to walk the line between a consumer device and an enterprise device,\" said Jon Erensen, research director at the technology specialists Gartner. \"People were hoping the initial limitations would be corrected with the update by now. The delay means they fall even further behind.\"