Owner willing to carry but bank isn't okay with it

[Riquelmi De La Rosaq]

So I found my first 4-plex in South Florida and I have been trying to close it for over a month now. The original plan was to buy it with the FHA 3.5% down program. I am from Florida and am currently working in NYC but planning to move back home in October. We got our clear to close after 6 weeks of letters, bank statements and explaining why I am working in NY and buying property in Florida. A few days later I hear that the Senior Underwriter has my file and is "asking for more information" 4 letters including 2 more from my local union in Miami later and she denied my loan. I was told that I needed to switch to a different loan program because the Underwriter didn't believe that I would be moving back to Florida to live in one of the four units. I was told by my broker that I could do a 15% down investment loan at 4% interest. This way the underwriter will push the deal through. I don't have enough cash for 15% down so I went back to the seller and asked him to hold a second mortgage for $20K for 12 months in order to get the deal done. He agreed today, I called my broker and he told me that we are good to go. An hour later he calls me back and tells me that the seller cannot carry the $20k and that I would have to come up with the full 15% down plus have 6 months PITI in reserves. He told me that "seller carry" is not an option because this is my first property. He went on to tell me that even at 20% down, seller carry wouldn't be an option.

For reference: Property price $280k so 15% down would be $42K seller would carry $20k and I pay the rest and have the 6 months PITI in reserves.

My questions are:  Am I dead in the water? Has anyone else run into this road block on their first deal? Is my issue lender specific? Would another lender be willing to let the seller carry the $20K?