Maybe I'm just stupid, but I am wondering whether my Resqme still works. How can I test it without shattering glass?

I had a Benchmade window breaker that, if pressed again something hard like a cardboard, releases the spike. So I tried the same thing with my Resqme. Nothing happened. Maybe the cardboard isn't hard enough. I tried a thick stack of paper. Nothing -- maybe too much give? I tried a hard plastic. Still nothing. Do I have a broken Resqme?

Those of you with Resqme: how do you test yours?