Page Speed recognizes expiers headers, but YSlow doesn't

We're running IIS6 on Windows Server 2003. Our s开发者_如何学运维ite is written in ASP.NET.

We configured our site to expire headers after 7 days. While Page Speed gives us a check for "Leverage browser caching", YSlow gives us an F on "Add Expires headers".

How can that be?

An example page can be found here

1. I don't see expiry or max-age headers either looking at either /schooltheme2010 nor Apps/WW/Page.aspx?ws=20068125-bc31-475c-906f-8b63aab03be3&page=3e96fc8a-0b11-410b-ade1-e9036203dbd2 (which is where I ended up after that).

2. Remember that Page Speed and YSlow are tools that offer guidelines (and I severely frown on YSlow's advice to turn off e-tags as 99.9999% of the time that makes things worse). You need to look at what's actually happening in detail yourself. Use Fiddler or something like that to view what is going on.

3. If Page Speed is saying "leverage browser caching" what makes you think it's seeing expires headers? Sounds to me like it's saying it doesn't.

4. Expires is overridden by max-age, which has a few advantages. There's no reason why you can't use both though.