Replacing Value of Empty Node in SQL XML

UPDATE  [Table] 
SET     [XmlColumn].modify(' insert text{"foo"} into (/root/node)[1]') 

Try out this work for me

Will this be of any help: http://whyiamright.wordpress.com/2008/01/02/updating-xml-column-in-sql-server-2005/?

You seem to miss slash in the begining of xpath.

EDIT: Then it seems to be a duplicate of this question:

Update Empty XML Tag in SQL Server