YUM repo problem: Metadata doesn't match

Installing Ajenti on CentOS 6 doesn't work because the checksum of the repodata file doesn't match.
Adding the repo works but interacting with it doesn't (yum -y update or yum -y install ajenti)

The install docs suggest to clean the metadata of yum, but that doesn't resolv the problem.
See the following output:

root@bleak: ~ # yum clean all
Loaded plugins: security
Cleaning repos: base epel extras ius remi updates
Cleaning up Everything

root@bleak: ~ # yum clean metadata
Loaded plugins: security
Cleaning repos: base epel extras ius remi updates
0 metadata files removed
0 sqlite files removed
0 metadata files removed

root@bleak: ~ # wget http://repo.ajenti.org/ajenti-repo-1.0-1.noarch.rp... && rpm -i ajenti-repo-1.0-1.noarch.rpm && rm ajenti-repo-1.0-1.noarch.rpm
2014-09-08 10:39:56 URL:http://repo.ajenti.org/ajenti-repo-1.0-1.noarch.rp... [3327/3327] -> "ajenti-repo-1.0-1.noarch.rpm.1" [1]
removed `ajenti-repo-1.0-1.noarch.rpm'

root@bleak: ~ # yum -y install ajenti
Loaded plugins: security
ajenti/primary | 27 kB 00:00
http://repo.ajenti.org/ng/centos/6/x86_64/repodata... [Errno -1] Metadata file does not match checksum
Trying other mirror.
Error: failure: repodata/primary.xml.gz from ajenti: [Errno 256] No more mirrors to try.

root@bleak: ~ # yum clean metadata
Loaded plugins: security
Cleaning repos: ajenti base epel extras ius remi updates
4 metadata files removed
0 sqlite files removed
0 metadata files removed

root@bleak: ~ # yum -y install ajenti
Loaded plugins: security
ajenti | 951 B 00:00
ajenti/primary | 27 kB 00:00
http://repo.ajenti.org/ng/centos/6/x86_64/repodata... [Errno -1] Metadata file does not match checksum
Trying other mirror.
ajenti/primary | 27 kB 00:00
http://repo.ajenti.org/ng/centos/6/x86_64/repodata... [Errno -1] Metadata file does not match checksum
Trying other mirror.
Error: failure: repodata/primary.xml.gz from ajenti: [Errno 256] No more mirrors to try.
root@bleak: ~ #

I've installed Ajenti a few days back and the problem didn't exist then.
Would be great if this could be resolved.

Cheers,
Stefan