As Terry said, you need to vent each trap/fixture. Wrapping it into the wet vent does not make it a vent, it makes it an alternate path for the waste from upstairs. You need to run that vent line higher up into where the line is above the fixtures above on the line. Code calls for 42" above the flood plane of the fixtures above. Look at the sample Terry posted. Ultimately, all of the vents tie into the one place, but that location is high up in the structure, above those drains above it.