Can anyone tell me what is wrong with this .INF file

I've been stuck on this all day, and have just run out of ideas.

I'm trying to run an installer from a CAB file initiated on a web page. I built a cab file that includes an installer (BlowbackInstaller.msi) and an inf file (see below).

The Problem:
When I hit the web page in IE8, it correctly prompts me that a control is trying to install and shows the correct signature information, so I know it is finding the CAB file and it is signed.

Then it correctly prompts me about whether I want to install it.
alt text http://www.freeimagehosting.net/uploads/cf19341e41.png

After I press the install button, it just continues processing the page without running the installer. I know this because the installer has several dialogs in it.

I tested the installer (msi) separately and it works just fine, it just seems like it isn't being launched from the CAB by IE. I suspect a problem in my INF file.

Here's the HTML to initiate it…

<object id="bbc" 
        codebase="../cabs/BlowbackControl.cab"   
        classid="clsid:A4748756-061D-11DF-9D94-BD9455D89593">
    <param name="_ExtentX" value="26" />
    <param name="_ExtentY" value="26" />
</object>

Here is the contents of the .inf file in the CAB.

[version]
signature="$CHICAGO$"
AdvancedINF=2.0 

[Setup Hooks]
hook1=hook1

[hoook1]
run=msiexec.exe /i %EXTRACT_DIR%\BlowbackInstaller.msi

Anyone see something obvious I am missing, or have any ideas for troubleshooting further?