Confirming what zehjotkah says, you need to update the firmware on your N900 first - either perform an over the air update (it should be available to you in Application Manager) or reflash your entire device by downloading the latest firmware image from Nokia.

The version you have is PR1.1, the over the air (OTA) update will upgrade you to PR1.1.1 (3.2010.02-8) and then to PR1.2 (10.2010.19-1). All your settings and data will be retained.

If the OTA update is not available, you need to download firmware PR1.2 (automatically using Nokia Software Updater on Windos, or manually on Linux/Mac) and flash your device, this will erase all your applications and settings so take a full backup first so you can restore them after the device has been updated.