I had this question after viewing XenApp
This was a previous question i submitted, I closed it before i had time to work this issue.
So what's happening is if you take a look at the screenshot i need to change the username. the current username is the old system admin, who no longer works here, in the last post they mentioned disabling this account would have no effect. However after disabling his account, Citrix Delivery Console is not able to discover anything, cant see the farm until we re enable his account.