Failing to colour a few SVG vector letters solid black

Hey,

I want to fill out letters for my typography which I first imported as a DXF and then saved as SVG. When I select the whole alphabet, 95% of the letters can be filled out correctly solid black, but some letters, inluding the "A" do not get coloured completely black, even though the path seems closed.

On the pictures you see the problematic "A" ,and the "B" as it should... 'be'. 

Thank you if you have an idea on how to fill it out.