What version of VP are you using? Try the latest.
If you are a registered user, remember that upgrades are free for up to six months. After that, your purchase will continue to fully function but a fee will be required in order to register the latest. Always retain the installer file, though it's automatically backed up on the PC.
If no joy, the best way to sleuth this is for you to share your project. Here's how... http://nch.invisionzone.com/topic/23659-tips-for-getting-help-on-this-forum/