Why am I getting this error when I use the nilValue in the data?

[Roger L Costello]

Hi Folks,

I have a field that is 2-20 characters in length. If no data is available, then 
the field is to be populated with a hyphen. Below is my element declaration for 
the field (it's the middle element). When I run the DFDL schema with this input:

John Doe/-/Sally Smith

I get this error message:

[error] Parse Error: Failed to parse infix separator. Cause: Parse Error: 
Separator '/' not found

Why am I getting that error?  /Roger

<xs:element name="Test">
    <xs:complexType>
        <xs:sequence dfdl:separator="/" dfdl:separatorPosition="infix">
            <xs:element name="A" type="xs:string" />
            <xs:element name="MessageIdentifier" type="xs:string"
                nillable="true"
                dfdl:nilKind="literalValue"
                dfdl:nilValue="-"
                dfdl:lengthKind="pattern"
                dfdl:lengthPattern="[A-Z]{2,20}">
            </xs:element>
            <xs:element name="B" type="xs:string" />
        </xs:sequence>
    </xs:complexType>
</xs:element>