在asp.net中配置Http模块的ETags。

i'm optimizing our company web site with seo optimization and yslow. but in yslow the ETAGS are F . I've gone through tens of web sites and tutorials and the best option was using an HTTP Module. I've done so and tried several modules but none shows results.maybe something in syntax is wrong or i'm registering it wrong .some say it is best to use app_PostReleaseRequestState instead of OnPreSendRequestHeaders because of a crash in heap.I've used both with no results. here it is : the file name is etag and it is in app-code folderi'm optimizing our company web site with seo op