I often see no bid price when I open a combo order, specially with butterflies. If I go over to the optionsXpress site and I can see both bid and ask prices for the same fly. For example, this is WLP 70/75/80 July call fly. In IB today, I got no bid, and ask was $2.85. The market is now closed, so I cannot see IB quote now. But in optionsXpress, it shows $2.50/$2.85. Any reason why?