The reason can be that you have unchecked the "Install Extras Manager" from the Skype advanced installation options. This means the Extras Manager is not installed and the "Extras" menu under tools remains grey.
To fix this re-install Skype again but click on the "Advanced" tab in the installation screen and make sure "Skype Extras Manager" is checked. After that the Extras menu should be active and you should see Pamela.
