Unique Particle Attribution with xsd:any and xsd:element with different namespaces

Hi,

 I am trying to create a choice with either a xsd:any from namespace A
or xsd:element from namespace B. I think that because they are from
different namespaces there should be no ambiguity, am I wrong?

My schema:

<?xml version="1.0" encoding="UTF-8"?>

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"
    targetNamespace="some-A"
    xmlns:tns="some-A"
    xmlns:fault="some-B"
    elementFormDefault="qualified" >

    <xsd:import namespace="some-B"
    schemaLocation="fault.xsd" />

    <xsd:element name="MyResponse">
        <xsd:complexType>
                <xsd:choice>
                    <xsd:any namespace="##targetNamespace"/>
                    <xsd:element name="Fault" type="fault:FaultType" />
                </xsd:choice>
        </xsd:complexType>
    </xsd:element>

When validating I get


XML validation started.
D:/zzz.xsd:33,8
ERROR: cos-nonambig: WC["some-A"] and "hsome-A":Fault (or elements
from their substitution group) violate "Unique Particle Attribution".
During validation against this schema, ambiguity would be created for
those two particles.

1 Error(s),  0 Warning(s).
XML validation finished.

What is the problem?