reverse proxy and query strings

I'm getting this error when traversing a link to a reverse-proxied
Domino server:

Proxy Error

The proxy server received an invalid response from an upstream server.
The proxy server could not handle the request GET /servlet/HiveCache.

Reason: Error reading from remote server

The link in question is this:
http://servername.com/servlet/HiveCa...7?opendocument

The Apache 2.0.54 error log records these errors:

proxy: error reading status line from remote server servername.com
proxy: Error reading from remote server returned by /servlet/HiveCache

The ProxyPass directive manual page indicates that the url element
"cannot include a query string" and my URL has two of them. Is there a
workaround for this? Perhaps something using mod-rewrite?

Thanks in advance,

Jeff