Molasses Mash Problem

[BosDistiller]

Hi, I have a molasses mash that is DOA. Wondering why. Any help you can provide would be much appreciated. Here is what I did: Created a gallon mash that was 21 brix. Added DAP. Tested the PH, which was 9.1 (its city water). Lowered the PH to 5, which is what the supplier's representative recommended, using lemon juice concentrate. Using four grams of yeast, I did a starter when the temp reached 40C. The stater was 500ml of mash with the four grams of yeast mixed in. I used an egg-beater to vigorously agitate the starter for ten minutes. I waited another fifteen. There was no action whatsoever. I added the starter to the remaining mash and agitate with the egg-beater some more. Nothing. It's three hours later and there is no action.....no bubbling in the airlock and no visible fermentation. There are also a few pools of brown blotchy skim on the surface of the mash that appears to be the yeast? I can't figure out where I went wrong. Thanks in advance.