Problem with multi valued attributes...

I have the following xacml rule : 

<Condition FunctionId="urn:oasis:names:tc:xacml:1.0:function:and"> 
        <Apply 
FunctionId="urn:oasis:names:tc:xacml:1.0:function:string-equal">
                <Apply 
FunctionId="urn:oasis:names:tc:xacml:1.0:function:string-one-and-only">
                        <SubjectAttributeDesignator 
AttributeId="urn:my-organization:security:names:subject:0.1:profil" 
DataType="http://www.w3.org/2001/XMLSchema#string"/>
                </Apply>
                <AttributeValue 
DataType="http://www.w3.org/2001/XMLSchema#string">1</AttributeValue>
        </Apply>
</Condition>

When I come with the following context, I get a permit decision :

<Attribute 
AttributeId="urn:my-organization:security:names:subject:0.1:profil" 
DataType="http://www.w3.org/2001/XMLSchema#string">
        <AttributeValue>1</AttributeValue>
</Attribute>

But if my attribut "profil" has more than one value, I have the following 
context and get an indeterminate decision :

<Attribute 
AttributeId="urn:my-organization:security:names:subject:0.1:profil" 
DataType="http://www.w3.org/2001/XMLSchema#string">
        <AttributeValue>1</AttributeValue>
</Attribute>
<Attribute 
AttributeId="urn:my-organization:security:names:subject:0.1:profil" 
DataType="http://www.w3.org/2001/XMLSchema#string">
        <AttributeValue>2</AttributeValue>
</Attribute>

How can I express my rule to get a permit decision in that case ?