ISPConfig can not know which templates you have installed as the slave can not report that back to the master, so you have to set it to the templates that you downloaded. According to the above ls output, you havent installed any templates yet. The record in the ispconfig interface is a demo record that has be changed to match your installed template.
e.g. for a debian 64bit template, run this on the slave:
and then adjust the template name in ispconfig to debian-6.0-amd64-minimal
Download a openvz template of your choice e.g. a debian template and then modify or add a record for that template in the ispconfig interface and create a openvz vm with it.