[YUM] YUM and Proxy issues

[ez]

[root at linux2 LAJAO]# yum update
Setting up Update Process
Setting up Repos
http://download.fedora.redhat.com/pub/fedora/linux/core/3/i386/os/repodata/repomd.xml:
[Errno 4] IOError: <urlopen error nonnumeric port: '8080?'>
Trying other mirror.
Cannot open/read repomd.xml file for repository: base
failure: repodata/repomd.xml from base: [Errno 256] No more mirrors to try.

I have the following in my yum.conf file, something still amiss:

proxy=http://172.17.4.16:8080
proxy_username=user
proxy_password=userpass

and I am currently using yum-2.2.1-1

Thanks...

ez