When you receive a system-message saying sth. like "Package not correctly signed" you probably have a old version of AndNav and need to deinstall the old one, before upgrading to the new version you just tried to install. To do so, please follow these steps:

If you can't get it work, please contact our support.   

Manual uninstall:

1. Navigate to your HOME-Screen.
2. Press the MENU button on your device.
3. Select "Settings" from the menu.
4. Select "Applications".
5. Select "Manage Applications".
6. Select "AndNav" from the list.
7. Hit uninstall in the screen that describes AndNav.