pairfind() with VSAs

I'm trying to write my own module and come into some problems. I'm trying to access request attributes using pairfind() as mentioned in the Wiki. I can get normal attributes without problem but having problem with VSAs. I tried to access some Cisco VSAs like h323-conf-id, h323-call-origin by using something like PW_H323_CONF_ID, CISCO_H323_CONF_ID, H323_CONF_ID but compiler told me those are "undeclared". How do I access those VSAs? Thanks. C.C. Hwang