Feed Variable Into Include Statement

i'm trying to change the following include statement :

<div id="contents">
<!-- #include file="includes/main_page.asp" -->
</div>

on an ASP page into something that receives the file name as a variable :

<div id="contents">
<!-- #include file="<%=fileToInclude%>" -->
</div>

however, this doesn't seem to work, as i get the following error message :

The include file '<%=fileToInclude%>' was not found.

it obviously is trying to find a file named <%=fileToInclude%> instead of seeing the variable my question is : is it possible to feed a variable into an include statement ?
if yes, how should i go about it ? if not, are there any alternatives ?