Table Sort function not working when table created in BehindFile

I am running a JavaScript table Sort function Within the header of my main ASP file:

<script src="sorttable.js"></script>

I am creating the table using my ASP BehindFile (via an AJAX call):

Response.Write("<table class=" & chr(34) & "sortable" & chr(34) & "border=" & chr(34) & "5" & chr(34) & ">")
Misc table data....
Response.Write("</table>")

The table comes out ok but the sort function is not enabled. The function worked when I was creating the table from my main ASP file, but when I moved it to the ASP BehindFile it stopped working.

Thanks