I'm curious as to how you contact them. Do you send a cookie cutter email to each journalist?
So, for example someone publicly vetting for someone else in some way. Just as a lot of sharing sites (i.e. couchsurfing) it must be possible to build up a reputation or to convey that you are serious.
Also, signing something that you will make the email fun to read or worth their while might be an option.
Just thinking out loud.
The ideal case would be journalists that organize this for themselves. "This is how you should contact me". :-)