ncsa versus iisw3c EXTRACT_EXTENSION gives different results

This works on IIS logs to filter out file extensions:

LogParser -i:IISW3C "SELECT COUNT(*) AS PAGEVIEWS FROM u_ex120529.log WHERE EXTRACT_EXTENSION(to_lowercase(cs-uri-stem)) NOT IN ('css';'ico';'js';'msi')" -q:ON –o:DataGrid

But, this same query does not work on Apache logs to filter out file extensions--it always gives total pageviews:

LogParser -i:NCSA "SELECT COUNT(*) AS PAGEVIEWS FROM access_log-20120912 WHERE EXTRACT_EXTENSION(to_lowercase(Request)) NOT IN ('css';'ico';'js';'msi')" -q:ON –o:DataGrid

I have tried different fieldnames. Any ideas why it does this?