DOCBOOK: Problem with "text import"

["Reinhold.Fuereder" <Reinhold.Fuereder@fhs-hagenberg.ac.at>]

I want to include a textfile into the document, be compatible with DocBook 5 and therefor use inlinemediaobject with imageobject.
When I use DocBook XML 4.1.2 in addition to jade & dsl stylesheets it does function well, but if I try the conventional DocBook 4.1 it does NOT include the textfiles while suppressing any errors too!

Here is a part of the DocBook 4.1 file:
--- snip ---

    <formalpara>
      <title>Source</title>
      <para>
        <programlisting>
          <inlinemediaobject>
            <imageobject>
              <imagedata fileref="src\isa.bdy" format="linespecific">
            </imageobject>
          </inlinemediaobject>
        </programlisting>
      </para>
    </formalpara>

--- /snip ---

Here are commandline invocations:

nsgmls -sv file.sgm
-> nsgmls:I: SP version "1.3.3"

jade -t rtf -d c:\docbook\docbook-dsssl-1.72\print\docbook.dsl file.sgm
-> [no error output; everything else in the rtf file is ok, but the including is ignored]


What's the cause for the difference in output?

Thank you,
  Reinhold