I think I saw on this board, but don't quote me on this, that they stopped offering the secured version of this card due to some political situation. I think that's a pity, because if they didn't approve you for the unsecured version, at least you could get the secured card, and later graduate to unsecured without losing account age.
I got mine in May with a $1,500 limit unsecured, when my highest limit on anything else was $500, and all of my other cards were secured. At that time, I think my scores were in the 600s. I didn't have a FICO score then for EX or TU, only for EQ. Why those DPs led to a $1,500 approval and your DPs led to a denial is a mystery to me, but I can't imagine you were denied by much. You probably could try again in a couple of months and get it. It's a really good card if you shop much at Amazon. Good luck!