Fetching serialized post_meta fields with XML-RPC

Hi,

I’ve got a scripts regularly downloading a listing of posts (from a custom post type) and some associated post_meta via XML-RPC. All was working fine, until I wanted to include an additional field which happens to be stored in a serialized form. This field is never included in the response. How can I get this field to be included as well?

Some additional info: I don’t know if this makes a difference or not, but I thought I’d also add that this field does not (necessarily) exist for all posts in the set.