He sent me an agreement to purchase real estate yesterday so I'm looking for the best approach.

Look at the last recorded deed, specifically the grantee and the area, if any, where it states where the future tax bills are to be sent.

I am the one who found the deal, I am the one who sent it to him asking him for something simple, accompany on site because I cant go by myself.

After I transferred him the money for the property, he sent me a Warranty Deed along with the house keys.

I sent him a full contract and then a number of addendums. 

Apply some moxie and "confirm" that you have the right address to send proposal to the registered owner to fix the citations that are being sent out (from the city).

I sent Brian a text message Friday (10/27) very respectfully explaining that I didn’t think we were a good fit, and that I was expecting a lot more structure with the content and coaching.

Instead, the seller gets another mailing after I already sent him an electronic contract to docusign, so on the verge of getting the deal. 

I sent dozens of emails.

Did all the usual stuff, found the owner on the county assessor's site, sent the owners mail (out of state owners, PO Box)..no response.