You have to vent the 2" separately...Originally Posted by sv_guy
The vent should be placed at the junction between the trap arm and riser...
(replace the 1/4 bend with a santee and the vent will work.)
This will also cure the S-Trap issue you do have
After putting in the santee, you can tie the vent into the 1-1/2" vent from the lav once it is at least 6" above the flood rim of that fixture...(we generally aim for about 42" for re-venting)