tinyXml no-English characters

Question

I'm working on a C++ MFC project on VS 2013. I'm using TinyXML library, utf-8 encoding.

I insert non-English characters like дąć and save the file. When I try to open this XML file TinyXML tell me there is an error:

Error #9: Unable to read end tag

XML file in question:

<GSE ldInst="1" cbName="InputGoose">
  <Address>
    <P type="APPID">0001</P>
    <P type="GoCBRef">�����</P>
    <P type="DatSetRef">�����</P>
    <P type="GoID">�����</P>
    <P type="MAC-Address">01-0C-CD-01-00-01</P>
    <SWE idx="0" dev="1">
      <State>P</State>
    </SWE>
  </Address>
</GSE>

What could be the problem?