Irule strange problem

I have tried this and the script is not working either. NOnetheless I think I found the root of the problem.

 

When I did debugging:

 

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when HTTP_REQUEST {

 

log local0. " URI: [HTTP::uri], Host: [HTTP::host] ,Path: [HTTP::path]"

 

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Sample log shows:

 

URI: http://www.bbb.com/aaaa, Host: ,Path: http://www.bbb.com/aaaa

 

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HTTP::host for some reason is not set, which is most probably the reason none of the if statements were matched.Any idea why HTTP::host is empty? How can I obtain the host which should be www.bbb.com?