Help needed creating a custom unit file (service) for swatch

I've installed swatch and it works fine when run from the command line, next step was to create a custom unit file for it, I have done this (see below) and when I run systemctl start swatch.service it works great, however, if I reboot the server it fails to start, and then if I start it manually I get this error

[/etc/systemd/system/swatch.service:8] Executable path is not absolute, ignoring: kill -s KI...tch.pid)
Hint: Some lines were ellipsized, use -l to show in full.

Here is the custom unit file

[Unit]
Description=Swatch Log Monitoring Daemon
After=syslog.target network.target auditd.service sshd.service

[Service]
ExecStart=/usr/bin/swatch --config-file=/etc/swatch/yum.conf --tail-file=/var/log/yum.log --pid-file=/var/run/swatch.pid --daemon
ExecStop=kill -s KILL $(cat /var/run/swatch.pid)
Type=forking
PIDFile=/var/run/swatch.pid

[Install]
WantedBy=multi-user.target

swatch is in /bin/swatch and /usr/bin/swatch - I've tried both and I get the same result.

There is a /root/.swatch_script.xxxx file create when running it from the command line, is this causing an issue?