PostMethod.setQueryString vs PostMethod.addParameter

Java 1.6
HttpClient 3.1
OS: Windows & Linux

I'm seeing some odd behavior, I am trying to POST to a website, using the
setQueryString method with my test data, it works fine all goes well.  Using
the addParameter(key,value)  , I get a post fail ( unfortunately the website
doesn't report what's going wrong ).

Normally I'd say fine I'll just use the setQuery , but the real world data
is much bigger, and I'm getting a URL that exceeds the standards when I try
to post.

Has anyone else seen or experienced this ?

Thanks,
Charlie
csanders@...