Can I assume you're referring to the Microsoft Windows Server 2008 Failover Cluster or Microsoft Windows Server 2012 Failover Cluster templates?
Please open the application and ensure the "Count statistic as difference" option is checked. There was an issue with an earlier version of this template where this setting was incorrectly left unchecked. It has been corrected in the latest version available through the Content Exchange. You can however set this option easily yourself, as pictured below.
