I bought iSale in a bundle via MacHeist too. I am trying to activate my account and am also being told the following:
"The Activation Code entered is invalid, because it is owned by another user.
Please press the "Back" button below to return and to make changes to the Activation Code."
I tried to send equinux a support question, but it just pops up a new tab with a blank screen when I try and send the message to them. Looks like its not being sent?
It also looks like many people have had this problem and it still hasn't been fixed.
How do we fix this problem???