juju lxd machine pending

I used the "juju bootstrap" command to set up my juju-controller on localhost. Then, I created a model named "test" and tried to create a machine using "juju add-machine". Furthermore, I attempted to deploy an LXD container with "juju add-machine lxd:0". Unfortunately, the machine "0/lxd/0" is still pending.I am not using MAAS.My juju version is 3.4.0-genericlinux-amd64.