Apple Watch 6 - Issue with Apps

just received my brand new 6 and have a question about the WhatsApp APP.

All the APPS on my iPhone have copied over on to my watch with no issues.

I have WhatsApp installed on my iPhone and when I receive a message it appears on my watch so the notifications are switched on.

My issue is that when I go find the APP on the grid and try and send a message the APP isn’t showing as an option??

Can anyone help?