[clue-tech] regexp question

[Dave Price]

Clueful Ones,

I have some files that have (what appear to be) unicode punctuation
characters that I need to mark-up as html.

I am trying to use vim to do a search and replace for characters like

?~@~Y  - which I want to substitute to something like  '

When I try   " :%s/?~@~Y/&#39/g "

In vim, I get an error: 

E33: No previous substitute regular expression      
E476: Invalid command

Any ideas as to what I need to escape in these substitutions to avoid the error?

Thanks.

aloha,
dave