Hi,
You can start troubleshooting as follows:
1) from the device cli try if you can ping the entitlement server:
ping nextwave.netscreen.com
If that fails you may have a DNS problem.
If the ping is successful, you have IP connectivity to the server.
2) do the following debug to find out why the retrieval fails:
debug httpfx all
clear db
exec license-key update (to trigger the key update)
... wait a few seconds to let it fail...
get db stream
Also check this:
http://kb.juniper.net/InfoCenter/index?page=content&id=KB13368
Gavrilo