fragment cache

[quique]

Hello

I have an aspx page with an ascx user control that i want
to cache(only the user control) acording to the value of
the parameter x that i send in the url.
In the declaration of the control i put the directive
<%@ OutputCache Duration="20" VaryByParam="x"%>

and in the aspx page that contains the user control i put
this directive
<%@ Register TagPrefix="uc1" TagName="ctrlPrueba2"
Src="ctrlPrueba2.ascx" %> to link the user control.

The problem is when i invoke the url passing the same
value in the parameter x as the time before, the desired
behavior is to return the cached user control, but it
don´t works... can anybody help me???

Thanks