Help needed: problem with installation: Undefined subroutine &Scalar::Util::weaken called at (eval 43) line 4.

Hi,
I am trying to install the Kwiki "2" via procedure explained on the
current home page (my system is Cygwin on w2k with the latest version
of
Perl)

1) Subversion step runs fine:
 svn checkout http://svn.kwiki.org/kwiki/trunk /usr/local/kwiki

2) Path setting works fine:
 export PATH=/usr/local/kwiki/bin:$PATH

3) And it dies here:
 kwiki -new /cygdrive/c/webs/kwiki2/cgi-bin
produces the error message:
 Undefined subroutine &Scalar::Util::weaken called at (eval 43) line
4.

What is wrong here, what shall I do to fix it?

Thanks,
John