Inline If/Then in VB.net?

Trying to figure out how to do an if/then in my .aspx (not my code behind).   I realize code behind would be best, but this isn't my code and I don't want to rewrite it all.  I just need to see if I can do an if/then on my .aspx.  I tried the following, but it didn't work.  Throws an error saying Code Blocks are not supported in this context.  Any suggestions?  I'm trying to add a parameter to a sql data source based on the value of a hidden field.
 
<% If hdnClientID.Value <> "" Then %> <asp:Parameter DefaultValue="10" Name="SectionID" /> <% Else %> <asp:Parameter DefaultValue="9" Name="SectionID" /> <% End If%>