WAXERR_3020 – A virtual directory with a different Application Pool than the parent Website and does not have script permissions 

Background: When an IIS virtual directory or virtual application is configured to use a separate application pool to the parent website, the Aptimize Website Accelerator must run in this context. If script execution permission is not allowed at this location, then attempts to execute the wax.axd handler that is used to service accelerated content requests may fail.

Solution 1: Change the application pool of either the parent website or virtual directory to be the same. This allows the Aptimize acceleration handler to execute in the same application context for both requests. 

Solution 2: For IIS 6, grant script execute permission for the virtual directory in the IIS management console - for IIS 7, ensure that the HTTP handlers section for the virtual application allows execution of the *.axd path.