IIS 7.5, Compression not working on one site
===

We have a server that has Compression enabled (both Static and Dynamic).
This works fine for all the sites on the box, but one (that happens to be Sitecore powered).

The applicationHost.config section is:

    <urlCompression doStaticCompression="true" doDynamicCompression="true" />
    <httpCompression directory="%SystemDrive%\inetpub\temp\IIS Temporary Compressed Files" noCompressionForProxies="false" staticCompressionEnableCpuUsage="90">
    <scheme name="gzip" dll="%windir%\system32\inetsrv\gzip.dll" />
    <dynamicTypes>
    <add mimeType="text/*" enabled="true" />
    <add mimeType="message/*" enabled="true" />
    <add mimeType="application/javascript" enabled="true" />
    <add mimeType="application/x-javascript" enabled="true" />
    <add mimeType="application/atom+xml" enabled="true" />
    <add mimeType="application/xaml+xml" enabled="true" />
    <add mimeType="*/*" enabled="false" />
    </dynamicTypes>
    <staticTypes>
    <add mimeType="text/*" enabled="true" />
    <add mimeType="message/*" enabled="true" />
    <add mimeType="application/javascript" enabled="true" />
    <add mimeType="application/x-javascript" enabled="true" />
    <add mimeType="application/atom+xml" enabled="true" />
    <add mimeType="application/xaml+xml" enabled="true" />
    <add mimeType="*/*" enabled="false" />
    </staticTypes>
    </httpCompression>

Enabling Failed Request tracing shows:

    <Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
     <System>
      <Provider Name="WWW Server" Guid="{3A2A4E84-4C21-4981-AE10-3FDA0D9B0F83}"/>
      <EventID>0</EventID>
      <Version>1</Version>
      <Level>4</Level>
      <Opcode>6</Opcode>
      <Keywords>0x40</Keywords>
      <TimeCreated SystemTime="2012-07-25T13:09:09.267Z"/>
      <Correlation ActivityID="{00000000-0000-0000-970C-0080000000D2}"/>
      <Execution ProcessID="1136" ThreadID="1548"/>
      <Computer></Computer>
     </System>
     <EventData>
      <Data Name="ContextId">{00000000-0000-0000-970C-0080000000D2}</Data>
     </EventData>
     <RenderingInfo Culture="en-GB">
      <Opcode>DYNAMIC_COMPRESSION_START</Opcode>
      <Keywords>
       <Keyword>Compression</Keyword>
      </Keywords>
     </RenderingInfo>
     <ExtendedTracingInfo xmlns="http://schemas.microsoft.com/win/2004/08/events/trace">
      <EventGuid>{E60CEE96-4472-448D-A13C-2170B18220EC}</EventGuid>
     </ExtendedTracingInfo>
    </Event>
    <Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
     <System>
      <Provider Name="WWW Server" Guid="{3A2A4E84-4C21-4981-AE10-3FDA0D9B0F83}"/>
      <EventID>0</EventID>
      <Version>1</Version>
      <Level>4</Level>
      <Opcode>8</Opcode>
      <Keywords>0x40</Keywords>
      <TimeCreated SystemTime="2012-07-25T13:09:09.267Z"/>
      <Correlation ActivityID="{00000000-0000-0000-970C-0080000000D2}"/>
      <Execution ProcessID="1136" ThreadID="1548"/>
      <Computer></Computer>
     </System>
     <EventData>
      <Data Name="ContextId">{00000000-0000-0000-970C-0080000000D2}</Data>
      <Data Name="Reason">2</Data>
     </EventData>
     <RenderingInfo Culture="en-GB">
      <Opcode>DYNAMIC_COMPRESSION_NOT_SUCCESS</Opcode>
      <Keywords>
       <Keyword>Compression</Keyword>
      </Keywords>
      <freb:Description Data="Reason">COMPRESSION_DISABLED</freb:Description>
     </RenderingInfo>
     <ExtendedTracingInfo xmlns="http://schemas.microsoft.com/win/2004/08/events/trace">
      <EventGuid>{E60CEE96-4472-448D-A13C-2170B18220EC}</EventGuid>
     </ExtendedTracingInfo>
    </Event>
    

There are no urlCompression or httpCompression details in the web.config etc of the application, and IIS Manager is showing that everything is enabled.

And as I say, it all works on other sites on this server.

Any thoughts?

Andy
