Thank you.
It didn't help. By adding @ to the Name I escaped the error message but didn't get a desired result! Why with the same expression XML:XPath get me good output?
Portion of the xml this sub will process:

<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>
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