"merge info for '<path>' maps to an empty revision range" error message when checking "include merged revisions"

Hello,
when I check "include merged revisions" in the log dialog,
I get the error: "merge info for '\path\' maps to an empty revision range"
and after that the log shows only few last revisions.
I afraid that this problem might cause us merge problems in future.

Does anyone knows how to solve this problem ? Is it a bug ? Does that mean
that our merge info is corrupt ?
Please help us.

Version info:

TortoiseSVN 1.5.5, Build 14361 - 32 Bit , 2008/10/24 18:06:34
Subversion 1.5.4,
apr 1.2.12
apr-utils 1.2.12
berkeley db 4.4.20
neon 0.28.3
OpenSSL 0.9.8i 15 Sep 2008
zlib 1.2.3

Thank you in advance,
Arcady.
Received on 2008-11-03 14:01:40 CET