server 2012 vdi pooled collections status says "Not Valid"

Hi I am trying to test a vdi with Server 2012. So far I have
1 Server with Virtualization Host
1 Server with RD Connection Broker, RD Session Host & RD Web Access

I have just created a Pool Collection with Windows 7 Sysprepped VM. In the Collections tab it says status as "Not Valid", I have followed this tutorial www.youtube.com/v/GJyM14dK-Mk and I dont know where I have mistaken.

Will be really grateful for someone's assistance please.