Sorting results of content search web part

Hi,

I configured a content search web part to return the subsites of a site. The results are appearing by rank which is not what I need in this situation, rather I'd like to sort the results alphabetically. Whenever I try to configure the web part sort parameters using a property such as Path, Title, SiteDescription or anything that is somewhat relevant to me, the query returns an error.

What am I doing wrong ? Note that I'm using O365 for hosting my sites.

Thanks in advance for any pointers,

Stephane

Stephane