Tomcat fails on first request in combination with jsvc

I have a web application where the first request may take a few seconds as some singletons are initialised.

I've used the mod_proxy and jsvc construction mentioned in this question and described on this page to connect apache with tomcat (data is served via SSL)

For the sample Tomcat application, everything works as it should. However, when using my application I get the following error in my apache log:

[Wed Feb 10 09:48:29 2010] [error] [client 130.12.1.26] (70014)End of file found: proxy: error reading status line from remote server localhost
[Wed Feb 10 09:48:29 2010] [error] [client 130.12.1.26] proxy: Error reading from remote server returned by /MyWebApp/MyWebApp.faces

and I get the following error in my tomcat output:

10/02/2010 09:48:29 9947 jsvc.exec error: Service exit with a return value of 1

I'm not an expert on this so I would like to know what's the cause of the problem and where I should look for an answer?