<OverallConnectionPoolStatus>
<FlowRater>
<Name>Total.IncomingReq</Name>
<Rate>0</Rate>
<LastMinRate>0</LastMinRate>
<Counter>209</Counter>
</FlowRater><FlowRater>
<Name>Total.RejectedReq</Name>
<Rate>0</Rate>
<LastMinRate>0</LastMinRate>
<Counter>0</Counter>
</FlowRater><FlowRater>
<Name>Total.AcceptedReq</Name>
<Rate>0</Rate>
<LastMinRate>0</LastMinRate>
<Counter>209</Counter>
</FlowRater><FlowRater>
<Name>Total.FailedSendResponse</Name>
<Rate>0</Rate>
<LastMinRate>0</LastMinRate>
<Counter>0</Counter>
</FlowRater><FlowRater>
<Name>Total.RejectedRetry</Name>
<Rate>0</Rate>
<LastMinRate>0</LastMinRate>
<Counter>0</Counter>
</FlowRater><FlowRater>
<Name>Total.IncomingRetry</Name>
<Rate>0</Rate>
<LastMinRate>0</LastMinRate>
<Counter>0</Counter>
</FlowRater><FlowRater>
<Name>Total.RejectedLastRetry</Name>
<Rate>0</Rate>
<LastMinRate>0</LastMinRate>
<Counter>0</Counter>
</FlowRater></OverallConnectionPoolStatus>
[download]

After reviewing your actual XML - it looks like your XPath is incorrect for your intentions. I don't see any attriubes in your XML.

Try something more like //OverallConnectionPoolStatus/FlowRater/Name/text() to reference your information.

The previous XPath's are attempting to search for attributes in the FlowRater node. What you actually have is a child node called Name with some information in it.

As far as why this works in some modules, and not in others I would postulate that the designer included this as a "feature" to help others out. - Or maybe you found a bug.

I still cant make it to work :(
The xpath expression you suggested:

//OverallConnectionPoolStatus/FlowRater/Name/text()
[download]

Still makes Twig crash! Why? it is a valid xpath expression!