FortiAnalyzer - FortiCare registration failed

Hi,

we have problems to register the trial license for the FortiAnalyzer VM.

The device is registered in our assets. But when I try to registered it in FortiCare during initial setup it fails with the error "The product serial number has already been registered". I found out, the the FortiAnalyzer has problem with the connection to server usfds1.fortinet.com.

We must use a web-proxy within the company network. Our Fortigates working fine with it but not the FortiAnalyzer.

DNS is working correctly.

Web-Proxy is set up and the VM is permit in the firewall to communicate with it.
The date/time is correct.

I also uploaded the license manual.

And any other connection seems to be working.

Any Idea to solve the problem.