"-" number of visit in custom variables of goal tracking

Support & Bugs
1

Hello,
in the custom variables of my goal, I see a strange number of visits “-” even with goal conversions.

What does it mean ? How a user could convert a goal without registering at least one visit ?

2

See FAQ Why are there sometimes 0 visits, but some conversions recorded, for example for a Keyword, a Website or a Custom Variable?

http://piwik.org/faq/general/#faq_117