This is my first rear-wheel drive car and my coupe does not want to go on ramps. As soon as I try to drive up the ramps, one or both of the ramps shoots forward about a foot.

Should I just put something heavy against the wheel ramps to prevent them from moving? Or am I doing something wrong here???

Update:
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I was wondering why everyone else with rhino ramps were having no problems putting their cars on the ramps, but my rhino ramps were shooting all over the place. So I looked at my rhinos and noticed that the rubber feet that were normally installed at the base of the ramps had both fallen off. I found the missing ramp rubber lying around in my garage and replaced them and now my rhinos are holding up my crossfire with ease. Thanks for those of you who gave me positive comments.