Hi,
Tpyo is right on this. The lowest click on Google is 1 cent. If an advertiser pays 1 cent for a click, there is obviously not much left to go around. If youlook at the RPM for these clicks, then you'll see that it is actually tallied, no matter how small the amount. These clicks normally happen on Asian clicks. As we are the only PPC company to pay you exactly what Google pays us for the click rather than estimating the value, then these things can happen whereas another provider may just pay whatever they believe you earned rather than you actually did earn.
This obviously happens in the other direction where Google pay us bigger than other parking providers estimate a click is worth.
Ed