How do I get the Sharepoint calendar web part to show more than 6 months of company calendar?

My company calendar is set up through Outlook and pulled into my SharePoint sites by groups.

I've tried through PowerShell using the following:

PS C:\Windows\system32> Set-MailboxCalendarFolder -Identity "user":\Calendar -PublishEnabled $true -PublishDateRangeFrom SixMonths -PublishDateRangeTo OneYear

Received this message:
WARNING: The command completed successfully but no settings of 'user:\Calendar' have been modified.

Any help would be appreciated. Thanks.