Q: When I use Siri on Sierra, I always get 'i don't see an app called X' even for Safari, Excel and other apps that are installed. How do I fix this?

I have installed Sierra on my iMac and am trying to use Siri. I can activate and get responses from Siri and get back simple responses to 'whats the date', 'whats the time' and even more complicated questions such as 'where is the statue of liberty'. However when I ask Siri to launch an app (any app) I always get 'you dont seem to have an app named XXX. We could see if the App Store has it'.