Vehicle Trigger Question

In the Vehicle Trigger video, it looked pretty easy to control the Rollback upfit and the truck, but when I tried in game, I couldn't figure out how to open the trunk or use the controls for the upfit. Am I missing something?

 

should be the left and middle mouse button

 

Have you ever played minecraft? In minecraft it uses a crosshair at the center of the screen to click. This is how the triggers work, there is no crosshair though so you have to sorta guess where the center of your screen is.
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Have you ever played minecraft? In minecraft it uses a crosshair at the center of the screen to click. This is how the triggers work, there is no crosshair though so you have to sorta guess where the center of your screen is.