http keepalive does not work

Hi there,

We use SoapUI 5.0.0
Build Date: 20140409-1012

With our SoapUI version http keepalive does not work.

On the Apache server side we see that soapui establishes a new connection for every request.
In der Apache log we also see the number of keepalive requests handled on every connection, which is always 0.

In the response we see that keep alive is supported from the server:
Keep-Alive timeout=5, max=100
Connection Keep-Alive

When we use another webservice java client, we see, that keep alive is working in the apache log.

In soapui we checked, that keep alive is not switch off:
File / preferences / Close connections after request: disabled
TestCase Options, Basic, Maintain HTTP session, enabled

Keep alive is enabled by default in soapui and java, but it does not work for us.

Any hints are really appreciated!

Thanks in advance

Nils