What proof do you have that this has not occurred? Please do your home work first so we can engage in intelligent discussion about this matter. Then talk to Mike Mulshine at investor relations, then call management at Company. Their were many days that I looked at the transaction log and saw that even know it was approximately 90% buys, the stock went down. This happened numerous times. I am not sure what your vested interest here is, but if you are serious about learning more about this, I highly recommend the links below.
Just total the volume of shares traded over any 6 month span pre-November 2006 and compare that to the current A/S (Go ahead and even assume that PBLS was diluting ALL of the A/S as some have and it still doesn't add up).