Not sure why, but the “Start only if the following network connection is available” option is disabled for scheduled tasks if the task is configured for: “Windows Server 2003, Windows XP, or Windows 2000”
With the options selected….
You can see the last “Network” option is disabled
Change the option to “Windows 7, Windows Server 2008 R2”
And then back to Conditions and now the Network dropdown is enabled
in
HTH,
Jon