I am developing simple application but getting this error

[athongen1]

SENT: <iq to="capstone-pc" type="set"><query xmlns="tst"><i fn="Anand" ln="Thonge"></i></query></iq>

RECV: <iq xmlns="jabber:client" xmlns:stream="http://etherx.jabber.org/streams" type="error" from="capstone-pc" to="12345@capstone-pc/Pandion"><query xmlns="tst"><i fn="Anand" ln="Thonge"/></query><error code="501" type="cancel"><feature-not-implemented xmlns="urn:ietf:params:xml:ns:xmpp-stanzas"/></error></iq>

[npetrele]

What are you using?  Jabber SDK/CAXL?  What Jabber server? 

The error message is telling you that the feature you are trying to use is not implemented at the server.