why does Reason Core Security idenitify setupnow.exe as a threat but Norton Security does not?

why does Reason Core Security idenitify setupnow.exe as a threat but Norton Security does not?  When I scan this file with Norton Security it say "No threats found" but Reason Core security identifies it as a Trojan.Genetic Installer.  see below"

"setupnow.exe

YOURUPDATER

DISPLAYTIME SOFTWARE

The application setupnow.exe by DisplayTime Software has been detected as Trojan.Generic.Installer. The program is a setup application that uses the NSIS (Nullsoft Scriptable Install System) installer. The file has been seen being downloaded from appdownloading.com and multiple other hosts."