In order to fix the issues, I suggest you download and install the latest version of the plugin for Revit 2014. Once you install it, launch the software, navigate to Add-ins > External tools > Revit To Lumion Bridge and export the files. If you still have issues, use the contact information from the official web page to get in touch with the developer.
Note: Also, you need to know that Revit To Lumion Bridge doesn't work with the LT versions of Autodesk Revit.