Explanation: This could have 3 different root causes.
1. This does not work in all browsers. Recommendation is to use Chrome.
2. The cluster manager needs to be able to communicate with Iray on port 9090.
3. Iray is actually not running.
Click on the Head Node Admin Page link in the upper right part of the website
If the page opens, Iray is running.
2. Check firewall settings on the VCA (iptables)
3. If Iray is not running - login to the machine (console or ssh)
Execute the corresponding run script manually and see if there is an error message