As Sebastian points out, to be able to say anything useful, it would
be very helpful to see your ODD file and input (at least the part
near "agent"). Either post them here, or put them on the web and send
a pointer here.
(Note that this list does not accept binary attachments, so you can't
zip them up and attach the compressed version.)
That said, is there a reason you're using a DTD rather than RELAX NG?
There are good reasons to use a DTD: e.g., your software only
supports DTDs, or you really want to use entities. But unless there's
a good reason, it is definitely best to use the RELAX NG schema
(whether XML or compact does not matter at all) to validate your
files. It is also a good idea to validate against the Schematron
schema *in addition* to the RELAX NG (or DTD).
> i'm a germanic philology student and i have a problem fixing an
> error of validation in TEI P5: i built my dtd with Roma, the sanity
> checker said it's ok, but when i tryed it in my xml doc, this error
> had appeared: Attribute "agent" must be declared for element. Does
> anyone know how i can fix it? thanks.