Then you might want to contact listia and see if there is something wrong. Sorry I didnt have that kind of problem before so I cant tell you why keep coming up invaild bid. After you bid did you click on the yes or no to confirm the bid? That is the last thing I could think of will come up invaild bid.
My daughter got it for her birthday, but doesn't use her ipod anymore since she can get free music now. She never used it, so there was no sense in letting it sit around. :)