This is very common when installing a new bracket for the new bumper style
You need to buy 2 new longer bolts of the same kind and go into town with it again
Unless otherwise as stated by Walt, there is a big possibility that the nut inside the mount fell off, and you will need to remove the rubber mount to get to it.
Easiest way to find out is to remove the bracket, and install the bolt by itself, and see if it starts going, and far enough to tighten up. If it does then determine the length needed to finalize the job, including the space needed for your bracket. Merry Christmas