Issue with Shortcodes or just doing something wrong

I’ve been trying to use shortcodes to display some of my custom fields. They work for displaying the current user’s name on a page, but when I post the custom field shortcode, nothing. The shortcode I’m coding using is:

[s2Get user_field=”Senator_2″ /]

I referenced http://www.s2member.com/codex/stable/s2member/api_functions/package-functions/#src_doc_get_s2member_custom_fields()

What am I missing?

http://ww.wp.xz.cn/plugins/s2member/