SSI And ASP Programming

i need some help to find a way to pas a asp variable in to the ssi include file commend

i have tryde to pass the varible like this:

<!--#include file="sets/<%=a1%>.asp" -->

that didn work for me so i tryed this way instead

a2 = "<!--#include file="sets/cenarion.asp" -->"

<%=a2%>

that didn want to wark either

im little lost how to get this to work im not sure if its even possible .

what im trying to do is pass the A1 varible to the include fille command couse A1 contains the name of the file. A1 gets its info from a request.querystring