'File not found: ...' during load

I'm having trouble with a dump-filter-load chain. I do:

svnadmin dump path/to/repos > dump
svndumpfilter include path1 ... < dump > dump-filtered
svnadmin load path/to/another/repos < dump-filtered

The first step works okay, nothing special there.

The second step, svndumpfilter, at first complained about some
paths that were copied to the selected paths - this looked just
like the issue described in the subversion book. I added those
paths from which the copy was made to the selection, i.e., listed
all of them after the 'include' keyword. It took several attempts
to figure them all out. Finally, svndumpfilter ran through.

I'm stuck now with the third and final step, svnadmin load. It
stops with the following message:

   <<< Started new transaction, based on original revision 1256
        * adding path : X/Y ...svnadmin: File not found:
          transaction '5832-4i2', path 'X/Y'

(I replaced the actual path names with 'X' and 'Y', respectively.)

At 'X/Y', there lies data that was imported using 'svnadmin load'
from a dump long ago. Might that be the cause? What can be done
about it?

Using subversion 1.6.0.

Thank you!
Lasse