There are two types of signal actuators: the new optical ones (lives on top of the light, and looks similar to a red-light camera), and the old magnetic ones. I'm pretty sure it's impossible to trigger a magnetic actuator unless you have a steel frame. Traffic authorities are supposed to adjust the sensitivity of the actuators, but they're not going to replace their whole system.

I'd give it longer than 45 seconds, too, many lights have a longer cycle than that!

Also, if you're at an intersection that has some traffic so there's a car behind you, pull way up so that they can trigger the light. A lot of times cars hesitate to get too close, so beckon, and holler at them if they don't get the message!