Boot release

I'm having trouble getting the boot release to work on my alarm. The alarm is an x-shield xs-800s. It has a -500 mA output for the boot/trunk release. I am using a relay to work the solenoid but its not working. I have set the relay up as discribed in this site, but still does not work. I have used a volt meter to make sure it is a negative output from the alarm and it seems it is. If I connect a negative wire from the chassis to the post on the relay which the alarm output connects to, it pops the boot/trunk, so the solenoid etc works ok. I've conneted my voltmeter to a positive source and used the alarm output an earth source and it gave me a reading straight away. When I pressed the button on the remote to pop the trunk it didnot change the reading. But when I connect the output back to the relay still nothing happens. This is really confusing me. How can I use it as an earth and get a reading without pushing the remote button but it still wont pop the trunk. Any Ideas??????????????

Do you have the relay like this

85= +12volts

86= - in from alarm for trunk release, this turns on the relay

87= ground to vehicle

30= trunk wire( must be Negative )

87a=not used

I have tried it like this but still no joy. The relay does not even make a noise like it is working. I've checked the relay by touching a chassis ground onto 86 and it works. I can only conclude that the alarm is at fault?

This is the image on the wiring diagram in the install manual does this look like a standard relay?