Chat trigger based on current URL with regex

I want to add a tag if the chat is started from a URL that contains a GUID…I've set it to look for this: https://website.website.com/meeting/^[a-zA-Z0-9]{8}-[a-zA-Z0-9]{4}-[a-zA-Z0-9]{4}-[a-zA-Z0-9]{4}-[a-zA-Z0-9]{12}$ but it isn't adding the tag. 

Wondering if the regex isn't correct? I need it to look for 8-4-4-4-12 with letters and numbers.

And yes, website.website is correct because I removed the actual website address for privacy.