IIS7 Module Only Works First Time?

I create an IIS Module that appends text to the page before it loads. When I go to the URL, this works perfect the first time the page loads. On subsequent loads, however, the text is never appended.

Any thoughts on how to remedy this?

== CODE ==

Here's my web.config:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
    <system.web>
        <compilation debug="true" />
    </system.web>
    <system.webServer>
        <modules>
            <add name="MIModule" type="MI.MyModule, MI" />
        </modules>
        <caching enabled="false" enableKernelCache="false" />       
    </system.webServer>
</configuration>

Some module code:

public void context_PreRequestHandlerExecute(Object source, EventArgs e)
        {
            HttpApplication app = (HttpApplication)source;
            HttpRequest request = app.Context.Request;

            string pageContent = app.Response.Output.ToString();

            string useragent = "HI!<br />" + pageContent + "<hr />" ;

            try
            {
                _current.Response.Output.Write(useragent);
            }
            catch
            {
            }
        }

and the rest of the code:

private HttpContext _current = null;

        #region IHttpModule Members

        public void Dispose()
        {
            throw new Exception("Not implemented");
        }

        public void Init(HttpApplication context)
        {
            _current = context.Context;

            context.PreRequestHandlerExecute += new EventHandler(context_PreRequestHandlerE开发者_如何学运维xecute);
        }

        #endregion

Is the _current variable actually HttpContext.Current? Is it a static field in your module? When/how is it initialized? My guess is that the empty catch clause gobbles up all errors, and following that thought, you most probably get a null reference on _current. Try removing the try/catch to learn more on what's wrong with your code