big ip cant take signature update by proxy...

hi guys
Does f5 consider new Policy for taking update for f5 bigip??!!

I have a f5 bigip i 10800,my f5 is behand a proxy for taking update from f5 server.
when my proxy wants to connect to downloads.f5.com for taking update and give update to bigip f5 it show me an eeror to my proxy
my f5 cant take signature update.
in below error show that f5 needs to authenticte when wants to connect to f5.downloads.com  and i have a question
what is problems?!!
Does f5 consider new Policy for taking update for f5 bigip??!!

Notes:
-my f5 bigip has license
-my f5 bigip has service contract
-my f5 has access to proxy.
-connection by telnet to proxy is ok
-my prxoy is in china 
for other site like cisco proxy does not back any erros.
1741686605.349    968 x.x.x.x TCP_TUNNEL_ABORTED/200 39 CONNECT downloads.f5.com:443 - HIER_DIRECT/107.162.230.156 -

Please Help:
Thanks