Hi, I'm currently building the bike up right now. I have tried three different front brakes and it seems like the hole is too small to fit one of those recessed nuts that come on brakes. Am I doing something wrong? I have a brake that worked fine on the back, it's just the front giving me troubles. I've attached a link to an example to show the nut i'm referring to. Also does anyone know the reach i should be getting? It seems rather long. Thanks for your help!

http://bit.ly/2aF8gDY