How to expand yasnippet snippet inside html file

How to expand yasnippet snippet inside html file

I have a lisp script that creates an empty html file:
(let ((mode "html-mode"))
(funcall (intern mode)))
(write-region "" nil "index.html")
Then i'm using yasnippet to generate the basic html file: I have a snippet
named "base" (i hit TAB key to expand it)
Is there a way to use this snippet in my lisp script?
i try, with no succes to use (yas/expand-snippet base)
Thanks.
Goulven.