Version 11 has a lot of dramatic changes under the hood which means that any older projects will not work. To help in upgrading your showfiles a project importer is built into version 11. To activate it you need to copy your old project into the Distrib/Projects folder. From the Ai software go to the project browser page and load the project from here. A popup box will ask you if you want to create a new v11 project based on your old project. This process will create a whole new file and leave your old showfile unaffected.
When installing a new version of Ai, it is advisable to either rename the existing Distrib folder or delete the Distrib folder altogether. If deleting the Distrib folder, please be sure to back up any user data in advance. Newer versions installed over the top of existing installations can create performance errors or system instability.