What is included in set #7155?
It is very common for Lego to pack larger parts like Plate 2 x 16 not in a seperate bag, for sets this size.

If I look at the inventory of set 7155, and compare this with sets I built over the years, I think 3 bags for the parts could be correct:


bag with minifig parts and small parts like 1x1's and 1x2's;
bag with large size parts like the 4x8 plates;
bag with remaining parts.