First, make sure that correct version of the Waves plugins are installed, relative to the version of Pro Tools that is installed. A list of supported hosts can be found here: www.wavesupport.net
If the correct versions are installed, then there may have been an error during the installation. Search your hard drive for a folder called "DDAE." If this folder exists, then copy the waveshell files inside it and paste them in: C: > Program Files > Common Files > Digidesign > DAE > Plugins. Relaunch Pro Tools.