How do I pass OleVariant to DocOutput.GetData

I am using the NNTP control and perform a listgroups command.

I get DocOutput callback and call the DocOutput.GetData function to retrieve
the data.

It is declared like this:

GetData( data: OleVariant; type_: OleVariant);

I call it like this:

    d, t : OleVariant;

    DocOutput.GetData( d, t );

    ... <snip>

It compiles just fine, but when the above line is executed I get an
OLEException 'Unsupported variant type'.

Can anyone tell me how to call the above function and actually have it work?