Remote start

Hi,my dad just bought a 1999 chevy silverado LS Z71 4x4 sportside used.It came with an after market remote starter.When we use the starter to start the truck the message center says SECURITY and will not go out unless you shut off the truck and start it back up with the key.Any idea why this is happening and how to correct the problem.Thanks

yes, either the Passlock2 bypass is not wired correctly or they didn't get BOTH ignition switches.