819 score and can't get a good mortgage loan

[Diane Trotter]

Can someone explain mortgage financing requirements in this case

1.  I am trying to buy 6618-6620 West 30th (called 2 on a lot but I thing they are separate lots)

2.  I wanted to put 10% or, if I had to, 20% down and consider it a 2nd home

3.  Colonial Financial told me I'd have to put 25% down because

     I have a primary residence and a rental property

Owner accepted offer of $95K on $99.9 listing

My score is 819 out of 830

I owe no one accept my Costco that I pay off every month

Why can't I get a loan.