Fragment caching Page cache

I have enabled page cache: Disk Enchanced. And I’m adding mfunc like so:

<!-- mfunc SECRETKEY echo rand(); --><!-- /mfunc SECRETKEY -->

It displays random number only on first refresh and then it disappears (the text is just displayed as a commented block of HTML code)

Is there any way to make work fragment caching with disk cache? Or should I use another caching method?

Thank you.

Using version: 0.9.2.9

http://wordpress.org/extend/plugins/w3-total-cache/