ldp.dsl

Friends,

I can't generate html files using ldp.dsl

What means this message?

openjade:/usr/local/sgml/dsssl/docbook-dsssl-1.76/html/ldp.dsl:355:18:E: 
reference to undefined variable "$table-width$"
openjade:/usr/local/sgml/dsssl/docbook-dsssl-1.76/html/ldp.dsl:320:28:E: 
reference to undefined variable "$verbatim-line-by-line$"

How can I solve it?

Thanks in advance.
Nei