Cant update connection string property from variable

Hi All

I am doing this:

http://microsoft-ssis.blogspot.no/2011/02/script-component-as-source.html

I have this example setup in a foreachloop which shreds a file name from a recordset into a variable.

All is working well. But I am trying to change the ConnectionString to the variable @[User::FileName] in the connection Expression properties. I have the variable changing from a foreachloop and have stepped through this to ensure the variable are changing. However this does not appear to be updating the Expression in connection property.

BTW I have the variable set as a  readwriteVariable in the script tranformation editor

Any ideas?

Thanks

BiF