[Plugin: WP SlimStat] human visits empty for sub-blogs

I got this message from one of my sub site admin, I can confirm that it is happening on all sub sites. I do have all the plugin requirements fulfilled.

Hi there,

I have noticed something strange with my stats. They are fine in general,
except I don’t believe there’s really that many people reading my shit, but
the visitors tab seems slightly broken.
The number of human visits is still 0, although I know it should at least be
three. All 1356 page views are counted as bots and the average pages per
visit is, like the longest visit, 0 pages.
Languages and IP addresses seem fine, the browser and OS stuff also and top
countries makes sense, too. The screen resolutions provide absolute numbers,
but no percentages at all, which makes sense given there’s not a single
human visit 😉
The graphs are also not available (no data to display) without humans
visiting my site.

The content tab also says “no data to display” for most things on there but
for most of them the reason is obviously the same as it must be on the
visitors page.