I can't get the -D option to work

[Costello, Roger L.]

Hello DFDL community,

When I invoke Daffodil, I want to dynamically feed into my DFDL schema a value 
for a variable.

I invoke Daffodil this way:

daffodil.bat parse
                -s label-message-characterization-2.dfdl.xsd 
                -r input
                -D Separator=,
                -o output/label-message-characterization-2.xml

That results in this error message:

[error] Bad arguments for option 'D': 'Separator=,' - wrong arguments format

How do I fix this?

Also, here's what I have in my DFDL schema to "catch" the value that I 
dynamically feed into the schema:

<xs:annotation>
    <xs:appinfo source="http://www.ogf.org/dfdl/";>
        <dfdl:format ref="default-dfdl-properties" />
        <dfdl:defineVariable name="Separator" type="xs:string" 
external="true">:</dfdl:defineVariable>
        <dfdl:defineFormat name="colonSeparator">
            <dfdl:format separator="{ $Separator }" 
                separatorPosition="infix" />
        </dfdl:defineFormat>
    </xs:appinfo>
</xs:annotation>

Is that correct?

/Roger