faultcode 105 faultstring xml error invalid document end line 1 column 1

[eluser]Unknown[/eluser]
Please can you help me? I have a problem which is when I acceed to the web service of joomla, it show me this error
<methodResponse>
<fault>
<value>
<struct>
<member>
<name>faultCode</name>
<value>
<int>105</int>
</value>
</member>
<member>
<name>faultString</name>
<value>
<string>
XML error: Invalid document end at line 1, column 1
</string>
</value>
</member>
</struct>
</value>
</fault>
</methodResponse>
I use joomla 1.5 which interact with phonegape application, please help me.