Upgrading using svn

I have a working version of RT on a windows platform (v3.0.12)
Tortoise SVN is also installed as SVN client

I wanted to upgrade this to the latest 3.4.xx version using SVN
but apparently the HTTP command PROPFIND is being blocked on the apache
server hosting the SVN tree ?
Should I change something in my SVN client config ?
I used ethereal to check the traffic between the SVN client and SVN

PROPFIND http://svn.autrijus.org/104/trunk HTTP/1.1
Host: svn.autrijus.org
User-Agent: SVN/1.1.3 (r12730) neon/0.24.7
Connection: TE
TE: trailers
Content-Length: 300
Content-Type: text/xml
Depth: 0
Accept-Encoding: gzip
Accept-Encoding: gzip

<?xml version="1.0" encoding="utf-8"?><propfind

1.1 405 Method Not Allowed
Via: 1.1 ISA
Connection: Keep-Alive
Proxy-Connection: Keep-Alive
Content-Length: 353
Content-Type: text/html; charset=iso-8859-1
Server: Apache/2.0.52 (FreeBSD) DAV/2 mod_perl/1.99_18 Perl/v5.8.6
Keep-Alive: timeout=15, max=100

405 Method Not Allowed

Method Not Allowed

The requested method PROPFIND is not allowed for the URL /104/trunk.

Apache/2.0.52 (FreeBSD) DAV/2 mod_perl/1.99_18 Perl/v5.8.6 Server at svn.autrijus.org Port 80

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