You can't use an include to get variables or scripts. It will not work, the server will parse in the content in the file b eing included but not execute it. Also, using an include tag within a <script> or <% code block %> will fail because they cannot be inside of them.
would be your only solution. If you want to call an external scripts you can use an external class, a code behind, or using script src
<script runat="server" language="VB" src="mycodefile.vb">