KEB2: "number of transfered records < number of read records" why?

Hi

I have an extractor 1_CO_PA_1000. When I go to R/3 and look in KEB2 I can see that less records are transfered than read for 1_CO_PA_1000. This is not the case for every request - some times every read record is transfered.

Does anybody have some ideas about how that can be?

Kind regards,

Torben