systemctl start vncserver@1 gives an error

vncserver@.service:

[Unit]
Description=Start TightVNC server at startup
After=syslog.target network.target

[Service]
Type=forking
User=**user**
PAMName=login
PIDFile=/home/**user**/.vnc/%H:%i.pid
ExecStartPre=-/usr/bin/vncserver -kill :%i > /dev/null 2>&1
ExecStart=/usr/bin/vncserver -depth 24 -geometry 1280x800 :%i
ExecStop=/usr/bin/vncserver -kill :%i

[Install]
WantedBy=multi-user.target

Error:

root@**server**:~# sudo systemctl start vncserver@1
Job for vncserver@1.service failed because the control process exited with error code.
See "systemctl  status vncserver@1.service" and "journalctl  -xe" for details.
root@**server**:~# sudo systemctl status vncserver@1
● vncserver@1.service - Start TightVNC server at startup
   Loaded: loaded (/etc/systemd/system/vncserver@.service; enabled; vendor preset: enabled)
   Active: failed (Result: exit-code) since Thu 2018-04-19 18:34:49 UTC; 18s ago
  Process: 3369 ExecStart=/usr/bin/vncserver -depth 24 -geometry 1280x800 :1 (code=exited, status=1/FAIL
  Process: 3364 ExecStartPre=/usr/bin/vncserver -kill :1 > /dev/null 2>&1 (code=exited, status=2)

Apr 19 18:34:49 **server** systemd[1]: Starting Start TightVNC server at startup...
Apr 19 18:34:49 **server** systemd[3364]: pam_unix(login:session): session opened for user **user** by (uid=0)
Apr 19 18:34:49 **server** systemd[3369]: pam_unix(login:session): session opened for user **user** by (uid=0)
Apr 19 18:34:49 **server** systemd[1]: vncserver@1.service: Control process exited, code=exited status=1
Apr 19 18:34:49 **server** systemd[1]: Failed to start Start TightVNC server at startup.
Apr 19 18:34:49 **server** systemd[1]: vncserver@1.service: Unit entered failed state.

Any idea what I’m doing wrong?